General Chemistry Flashcards

Question

What is homogenous catalysis? What is heterogenous catalysis?

Answer 1

Homogenous catalysis: the catalyst is int he same phase (solid, liquid and gas) Heterogenous catalysis: the catalyst is in a distinct phase

Answer 2

Materials composed of atoms with unpaired electrons will orient their spins in alignment with a magnetic field, and the material will thus be weakly attracted to the magnetic field

Answer 3

Ionic radii tend to decrease in size across a period (row) of the periodic table (left to right) and increase moving down a group (column).

Answer 4

- Increase the reactio nrate without themselves being consumed int he reaction Work by: - increasing the frequency of collisions between the reactants - changing the relative orientation of the reactants and thus making a higher percentage of collisions effective - donating electron density to the reactants - reducing intramolecular bonding within the reactant molecules

Answer 5

- When atoms that have identical or nearly identical electronegativites share elecron pairs, they equally distribute these electrons, creating a nonpolar covalent bond - Note that only bonds between atoms of the same element will have exavtly the same electronegativity and therefore exhibit a purely equal distribution of electrons - Any bond between atoms with a difference in electronegativity less than 0.5 is generally considered nonpolar

Answer 6

The enthalpy change associated with the combustion of a fuel - Determined in a similar fashion to that of Hess's Law

Answer 7

**ΔG_rxn** - the free energy change of the reaction is the difference between the free energy of the products and the free energy of ther reactants - negative free energy indicates an exergonic reaction (energy is given off) - positive free energy changes indicates endergonic reaction (energy is absorbed)

Answer 8

H₂ N₂ O₂ F₂ Cl₂ Br₂ I₂ - These are perfect examples of nonpolar covalent bonds

Answer 9

- Materials consisting of atoms that have all paired electrons will be slightly repelled by a magnetic field and are said to be diamagnetic

Answer 10

methyl red: goes from red to yellow, pH 4 to 6 bromothymol blue: goes from yellow to blue, pH 6 to 7.5 phenolpthalein: goes from clear to hot pink, pH 8 to 10

Answer 11

- A molecule which does not appear in the overall reaction - Often difficult to detect experimentally because they may be consumed almost immediately after they are formed Example: Step 1: A₂ + B → A₂B Step 2: A₂B + B → 2AB Overall Reaction: A2+2B →A2B - A₂B is the intermediate in this reaction

Answer 12

- When an acid and base react with each other to form a salt and often (but not always) water HA + BOH ⇔ BA (s) + H₂O Example: HCl +NaOH ⇒ NaCl +H₂O

Answer 13

E= -R_H/n² R_H: Rydberg unit of energy; 2.18 x 10-18 J/electron n: principal quantum number of the electron

Answer 14

HF CH₃OOH CH₃OH

Answer 15

Coupling is a common method for supplying energy to nonspontaneous reactions, by coupling a sponteaneous reaction to a nonspontaneous one Example: the combustion of glucose is exergonic; the formation of peptide bonds is endergonic - Energy from the combustion of glucose can be stored in the bonds in GTP, which are then lysed to provide the energy for forming peptide bonds

Answer 16

_standard conditions_: has been defined for measuring the enthalphy, entropy and Gibbs free energy changes of a reaction - used for kinetics, equilibrium and thermodynamics problems **Standard Conditions: 25˚C, 1atm and 1 M concentrations** Standard temperature and pressure (STP): use for ideal gas calculations **STP : 0˚C and 1atm**

Answer 17

XA= moles of a/ total moles of all species - The sum of mole fractions in a system will always equal one Example: If 184 g of glycerol (C3H8O3, 92g/mol) is mixed with 180g water (H2O, 18g/mol), what is the mole fractions of the two compounds 180g water x 1mol/18g= 10 moles of water 184g of glyerol x 1mol/92g = 2 moles of glycerol 10+2=12 total moles 10/12 = 0.83= mole fraction of water 2/12 = mole fraction of glycerol

Answer 18

The difference in energy between two shells decreases as the distance from the nucleus increases because the energy difference is a function of

Answer 19

**rate = Z x f** Z: total number of collisions occuring per second f: fraction of collisions that are effective Remember: - Collision theory of chemical kinetics states that the rate of a reaction is proportional to the number of collisions per second beween reacting molecules - Also suggests, however, that not all collisions result in a chemical collision - Effective collision (one that leads to the formation of products) only occurs if the molecules collide with each other int he correct orientation and with sufficient energy to break their existing bonds and form new ones

Answer 20

- Group VIIIA or Group 18 - Inert gases because they have miminal chemical reactivity due to their filled valence shells - Have high ionization energies, little or no tendency to gain or lose elctrons and, for most of them, no mreasurable electronegativity - Extremely low boiling points and exist at gases at room temperature

Answer 21

When the central cation is bonded to the same ligand multiple places - Requires large organic ligands that can even double back to for m a second or third bond with the central cation - Chelation therapy is ften used to sequester toxic metals

Answer 22

- Reduces the E_a - A catalyst decreases the energies of activation, E_a, for both the forward and reverse reactions - Catalysts have _no impact_ whatosever on the equilibrium position or the measurement of K_eq - Do not change a non-spontaneous reaction into a spontaneous reaction

Answer 23

- For a given gaseous sample held at constant temperature (isothermal conditions), the volume of the gas is inversely proportional to its pressure PV=k (a constant) or P₁V₁=P₂V₂ As pressure increases, volume decreases

Answer 24

- The concentrations of pure solids and pure liquids do not appear in the equilibrium constant expression - This is because the equilibrium is based on the activities of compounds, not on concentrations; the activities of pure solids and liquids are defined to be 1

Answer 25

C₂H₃O₂^-

Answer 26

The difference between the number of electrons assigned to an antom in a Lewis strucutre and the number of electrons normally found in that atom's valence shell is the formal change Formal Charge= V - N_nonbonding + 1/2N_bonding V: normal number of electrons in the atom's valence shell N_nonbonding

Answer 27

- Any molecule with an odd number of valence electrons cannot distribute those electrons to give eight to each atom - Example: NO has 11 valence electrons

Answer 28

corresponds to the number of particles into which a compound dissacoiates in solution Example: For NaCl, i=2, since in solution, for every NaCl, we get 1 Na⁺ and 1 Cl^- and 1+1=2

Answer 29

It is impossible to simultaneously determine, with perfect accuracy, the momentum and the position of an electron - - If we want to assess the position of an electron, the electron has to stop (thereby removing its momentum); if we want to assess its momentum, the electron has to be moving (thereby changing its position)

Answer 30

An electrochemical cell that drives a non-spontaneous redox reaction through the application of electrical energy - They are often used to decompose chemical compounds, in a process called electrolysis ΔG \> 0 emf= negative Example: Electrolytic cells can be used to drive the nonspontaneous reaction of water into oxygen and hydrogen gas

Answer 31

A process which can occur by itself without having to be driven by energy from an outside source - Calculating the change in Gibbs Free energy (ΔG) for a reaction will allow us to determine if the process is spontaneous - Note: spontaneous reactions may not necessarily happen quickly or go to completion

Answer 32

- The temperature at which the vapor pressure of the liquid equals the ambient pressure - Since adding a solute to a solvent results in a decrease in the vapor pressure of the solvent, then more energy and thus higher temperature will be required before its vapor pressure equals the ambient presssure ΔT_b= iK_bm ΔT_b: increase in boiling point i: van't Hoff factor Kb: is a proportionality constant characteristic of a solvent (given on test day) m: molality

Answer 33

- A system which can exchange both energy (heat and work) and matter with the surroundings Example: pot of boiling water

Answer 34

_**Q \< K_eq**, the foward reaction has not yet reached equilibrium_ - There is a greater concentration of reactants and smaller concentration of products than at equibrium - The forward rate of reaction is increased to restore equilibrium _**Q = K_eq**, then the reaction is in dynamic equilibrium_ - The reactants and products are present in equilibrium products - The forward and reverse reactions of reaction are equal _**Q \> K_eq**, then the forward reaction has exceeded equilibrium_ - There is a greater concentration of products and a smaller concentration of reactants, then at equilibrium - The reverse rate of reaction is increased to restore equilibrium

Answer 35

- A species which reacts like an acid in a basic environment and like a base in an acidic environment Example: Water (H₂O) - In the present of a base, H₂O + B- ⇔HB + OH^- - In the presence of an acid, HA + H₂O ⇔ H₃O⁺ + A^-

Answer 36

Chiral centers are tetrahedral atoms (usually carbons) that have four different substituents Stereoisomers= 2ⁿ Where n= number of chiral centers

Answer 37

- Yes, K_eq is a characteristic oaf a particular reaction at a given temperature; the equilibrium constant is temperature-dependent

Answer 38

- **Endothermic process**: processes in which the system absorbs heat ΔQ \> 0 - **Exothermic process**: proccesses in which the system releases heat ΔQ \< 0

Answer 39

- The sum of the protons and neutrons in the atoms nucleus

Answer 40

Each of two or more compounds differing only in the spatial arrangement of their atoms - same connectivity of atoms, just different spatial arragements

Answer 41

- Electrons move from anode to cathode - Current runs from cathode to anode

Answer 42

- physical properties of solutions that depend on the concentration of dissolved particles but not on their chemical identity - Includes: vapor pressure depressure, freezing point depression, boiling point elevation and osmotic pressure

Answer 43

- the lowest s subshell is 1s - the lowest p subshell is 2p - the lowest d subshell is 3d - the lowest f subshell is 4f

Answer 44

- Anode: Where oxidation occurs Cathode: where reduction occurs Mneumonic: AN OX and RED CAT

Answer 45

- most elements exist as two or more isotopes, and these isotopes are usually present in the same proportions in any sample of a naturally occurring element - the weighted average of these different isotopes is the atomic weight

Answer 46

- Since liquids and solids are essentially incompressible, only chemical reactions that involve at least one gaseous species will be affected by changes in the system's pressure and volume - When a system is compressed, its volume decreases and pressure increases , resuling in the system no longer being in equilibrium state - The system will move forward or in reverse, always toward whichever side has the lower total number of gas moles; if one increases the pressure in a system, it will respond by decreasing the total number of gas moles, thereby decreasing the pressure (This is a product of the ideal gas law, which tells us there is a direct realtionship between the number of moles of gas ant eh pressureof the gas)

Answer 47

- The enthalphy change acompannying a reaction being carried out under standard conditions ΔH°rxn = ΣΔH°f, products - ΣΔH°f, reactants

Answer 48

**Found** - On the upper right side of the periodic table **Characteristics** - Brittle - Show little or no metallic luster - Atomic level: high ionization energies, electron affinities, and electronegativities as well as small atomic radii and large ionic radii - Thus, poor conductors of heat and electricity - Inability to give up electrons

Answer 49

- The electrons that are farthest from the nucleus have the strongest interactions with the surrounding environment and the weakest interactions with the nucleus

Answer 50

Power = Force x time Power = IV Power = Energy/time

Answer 51

- The greater the concentration of the reactants, the greater the number of effective collisions per unit time - This leads to an increase in the frequency factor (A) of the Arrhenius equation - The reaction rate will increase for all but zero-order reactions - For reactions occuring in the gaseous state, the partial pressures of the gas reactants erve as a measure of concentration

Answer 52

- Uses Lewis dot structure to predict the molecular geometry of covalently bonded molecules - States that the three-dimensional arrangement of atoms surrounding a central atom is determined by the repulsions between bonding and non-bonding electron pairs in the valence shell of the central atom - Electron pairs arrange themselves as far apart as possible, thereby minimizing repulsive forces

Answer 53

- States that any pure ample of a given compound will contain the same elements in identical mass ratio - For example: every sample of water will contain two hydrogen atoms for every one oxygen atom; or, in terms of mass, for every one gram of hydrogen, there will be eight grams of oxygen

Answer 54

- In subshells that contain more than one orbital, such as the 2p subshell with its three orbitals, the orbitals will fill according to Hund’s rule, which states that, within a given subshell, orbitals are filled such that there are a _maximum number of half-filled orbitals with parallel spins_

Answer 55

- A type of intermolecular force - Polar molecules orient hemselves in such a way that the opposites charged ends of the respective molecular dipoles are closest to each other: the positive region of one molecule is clsoe the the negative region of another molecule - This arrangement is energetically favorable because an attractive electrostatic force is formed between two molecules - Dipole-dipole are present in soldi and liquid phases but become negligible in the gas phase because of signficantly increased distance between gas particles - Note: polar species tend to have higher melting and boiling points because of dipole-dipole interactions

Answer 56

- drop the end of the name of the element and add **-ide** _Examples_ H^- is hydride F^- is flouride O₂^- is oxide S₂^- is sulfide N₃^- is nitride P₃^- is phosphide

Answer 57

The amount of a compound, measured in grams, that produces one equivalent of the particle **Gram equivalent weight = Molar mass/ n** n: the number of particles of interest produced or consumed per molecule of the compound in the reaction Example: One woud need 31 grams of H₂CO₃ (molar mass of 62g/mol) to produce 1 equivalent of hydrogen ions, because each molecule of H₂CO₃ can donate two hydrogen ions (n=2)

Answer 58

- the spin of the electron - has two spin orientations designated +1/2 and - 1/2 - m_s - Whenever two electrons are in the same orbital, they must have opposite spins. - In this case, they are often referred to as being paired - Electrons in different orbitals with the same ms values are said to have parallel spins.

Answer 59

- When the difference in electronegativites between two atoms is between 0.5 and 1.7, a polar covalent bond is formed - This results in the more electronegative atom acquiring a greater portion of the electron density, giving rise to a _partial negative charge (_𝛿^-) - The less electronegative element will acquire a smaller portion of the electron density, givint it a _partial positive charge (_𝛿⁺)

Answer 60

- A substance which will dissociate to form an excess of OH^-

Answer 61

Dynamic equilibrium: when a reaction has reached its equilbrium but the forward and reverse reactions still continue, they just occur at the same rate Static equilibrium: when a reaction has reached its equilbrium and the forward and reverse reactions have stopped

Answer 62

- The slowest step in any reaction - Acts like a kinetic bottleneck, preventing the overall reaction from proceeding any faster than the slowest step

Answer 63

- electrons in different orbitals with the same ms values are said to have parallel spins

Answer 64

- When one or more electrons from an atom with low ionization energy, typically a metal, are transferred to an atom with high electron affinity, typically a nonmetal - The resulting electrostatic attraction between opposite charges is what holds the ions together Example: NaCl

Answer 65

- When two atoms with relative difference in eletronegativities come together in a covalent bond, they must negotitae the degree to which the electron pair will be shared - The atom with the higher electronegativity gets the larger share of the electron density - The polar bonds creates a dipole, with the positive end of the dipole at the less electronegative atomand thenegative end at the more electronegative atom

Answer 66

An electron pair acceptor

Answer 67

For a generic reversible reaction aA + bB ⇔ cC +dD, the law of mass action states: - if the system is at equilibrium at a constant temperature, then the following ratio is constant **K_eq= [C]^c[D]^d/ [A]^a[B]^b**

Answer 68

- The transfer of energy from one substance to another as a result of their differences in temperature - Zeroth Law of Thermodynamics: objects are in thermal equilibrium only when their temperatures are equal Heat: process function not a state function

Answer 69

- Analogous the the reaction quotient, Q, when referencing the equilibrium constant, K_eq Given AmBn ⇔ mAn+ (aq) + nBm- (aq) IP = [Aⁿ⁺]^m[B^m-]ⁿ If IP \< K_sp, the solution is unsaturated If IP \> K_sp, the solution is supersaturated If IP = K_sp, the solution is saturated

Answer 70

**ΔG° = -nFE°_cell** ΔG° : standard charnge in free energy n: number of moles of electrons exchanged F: Faraday's constant E°_cell: standard emf of the cell - This is the change in teh amount of energy avialable in an electrochemical cell to do work

Answer 71

Bonding electrons: the electrons which are involved in covalent bonding, located in the valence shell Non-bonding electrons: any electorn not in the valence shell, which are not involved in covalent bonding

Answer 72

P/T = k or P₁/T₁= P₂/T₂ If the number of moles and volume is held constant, the pressure is is proportional to the temperature

Answer 73

- The average energy that is required to break a particular type of bond between atoms in the gas phase - An endothermic processes Units: kJ/mol of bonds broken - This can be an extension of Hess's Law: The enthalphy change in a reaction is also a product of the bonds broken (endothermic) and bonds formed (exothermic) ΔH°rxn = ΣΔH_{bonds broken}- ΣΔH_{bonds formed} = total energy absorbed - total energy released

Answer 74

- The presence of solute particles in a solution interferes with the formation of the lattice arrangement of solvent molecules associated with the solid state - Thus, a greater amount of energy must be removed from the solution, resulting in a lower temperature, in order for a solution to solidify ΔT_f= iK_fm ΔT_f: freezing point depression i: van't Hoff factor K_f the porportionality constant m: molality of the solution

Answer 75

- The atomic radius of an element is equal to one-half of the distance between the centers of two atoms of an element that are briefly in contact with each other **- Atomic radius decreases from left to right** - As we move left to right, protons and electrons are added; because the electrons are being added only to the outermost shell and the number of inner-shell electrons remains the same, the increasing positive charge of the nucleus pulls the outer more elctrons more closely **- Atomic radius increases down a group** - The increasing principal quantum number implies that the valence electrons will be found further away from the nucleus because the number of inner shells is increasing, separating the valence shell from the nucleus

Answer 76

The flow of as particles under pressure from one compartment to another, through a small opening - For two gases at the same temperature, the rate of effusion are proportional to the average speeds and these reates of effusion, in terms of molar mass, is the same as that for diffusion

Answer 77

- Known as the representative elements - Include groups IA through VIIIA - The elements in these groups have their valence electrons in the orbitals of either s or p subshells

Answer 78

- shorthand notation for representing the reactions in an electrochemical cell Rules: 1. The reactants and products are listed from left to right in this form: anode| anode solution (concentration) || cathode solution (concentration) | cathode 2. A single vertical line indicates a phase boundary 3. A double verticle line indicates teh presence of a salt bridge or some other type of barrier

Answer 79

- The difference in potential (voltage) between two half cells under standard conditions **E°_cell= E° _{red, cathode} - E°_{red, anode}**

Answer 80

- When a weak base is placed in aqueous solution, it will only partially dissociate; thus, there will be an equilibrium between the associated and dissociated components BOH (aq) + H2O (l) ⇔ B+ (aq) + OH- (aq) K_b= [B⁺] [OH^-] / [BOH] - The smaller the K_b, the weaker the acid and the less it will dissociate - K_b \< 1 is a weak base

Answer 81

- Under standard conditions, the most stable form a substance is called the standard state of a substance Common standard states to know: H₂ (g) H₂O (l) NaCl (s) O₂ (g) C (s, graphite)

Answer 82

- An atoms tends to bond with other atoms so that it has eight electrons in its outermost shell, thereby forming a stable electron configuation similar to that of the noble gases **Exceptions** - Hydrogen: which can only have two valence electrons - Lithium which bonds to attain two valence electrons - Beryllium which bonds to attain four valence electrons - Boron which bonds to attain six valence electrons - All elements in period 3 and greater, which can expand the valence shell to include more than eight electrons by incorporating d-orbitals

Answer 83

- Whenever two electrons are in the same orbital, they must have opposite spins. - In this case, they are often referred to as being paired

Answer 84

NaOH KOH Ca(OH)₂ Mg(OH)₂

Answer 85

- Adiabatic processes occur when no heat is exchanged beween the system in the environment; thus the thermal energy of the system is constant throughout the process (Q=0) If Q=0, then ΔU = 0 - W, and thus, **ΔU = - W**

Answer 86

- Describe a system in equilbrium state - Cannot describe the process of the system, i.e. how the system got to its current equilibrium - Are only useful for comparing one equilibrium state to another - are path indepdendent, but are not necessarily independent of one another _State functions include:_ - pressure (P) - density (ρ) - temperature (T) - volume (V) - enthalpy (H) - internal energy (U) - Gibbs free energy (G) - entropy (S)

Answer 87

- the ground state of an atom is the state of lowest energy, in which all electrons are in the lowest possible orbitals - orbit with the smallest, lowest-energy radius was defined as the ground state (n = 1)

Answer 88

- The tail is at the positive end and the head of the arrow is at the negative end

Answer 89

- defined as the amount of energy required to raise the temperature of one gram of a substance by 1 degree Celsius Specific heat of H2O: 1 cal/g x K

Answer 90

- Groups IB to VIIIB - Considered to be metals; low electron affinities, low ionization energies and low electronegativites - High melting and high boiling points - Tend to be quite malleable and are good conductors due to the loosely held electrons that progressively fill the d-orbitals in their valence shells - Unique characteristic: many of them can have different possible charged forms (oxidation states)

Answer 91

**molM = It/nF** mol M: the amount of metal ion being deposited at a specific electrode I: current t: time F: Faraday constant (96,485C/mol e^-) Mneumonic: calculating **Moles of M**etal, **It** is **N**ot **F**un

Answer 92

- These are the atomic emission spectrum for hydrogen, when going down one **Lyman series**: The group of hydrogen emission lines corresponding to transitions from energy levels n ≥ 2 to n = 1 **Balmer series**: The group of hydrogen emission lines corresponding to transitions from energy levels n ≥ 3 to n = 2 - includes four wavelengths in the visible region. **Paschen series**: The group of hydrogen emission lines corresponding to transitions from energy levelsn ≥ 4 to n = 3.

Answer 93

- Some moleucles are more likely to react with each other in aqueous environment, while others are more likely to react in nonaqueoues solvents - The physical state of the meidium (liquid, gas, solid) can also have a effect - Generally, polar solvents are preferred because their dipole tends to polarize the bonds of the reactants, thereby lengthening and weakening them, permitting the reaction to occur faster

Answer 94

- Elements which are stable with fewer than eight electrons in their valence shell - Hydrogen (stable with 2 electrons) - Helium (2) - Lithlium (2) - Beryllium (4) - Boron (2)

Answer 95

- The Gibbs Free Energy of the reaction - Note that whether or not the reaction happens does not have an impact on how fast the reaction occurs

Answer 96

- A technique used to measure transferred heat - Example: bomb calorimeter or decomposition vessel - A sample of matter, typically a hydrocarbon, is placed in the stell decomposition vessel, which is then filled with almost pure oxygen gas - The decomposition vessel is then placed in an insultated container holding a known mass of water - The contents of the decomposition vessel are ignited by an electronic ignition vessel - The material combusts in the presence of oxygen and the heat that evolves is the heat of the combustion reaction - Because W= PΔV and the volume is constant, no work is done Because no heat is exchanged betweeen the calorimeter and the rest of the unvierse, ΔU_system+ ΔU_surroundings = ΔU_calorimeter = Q_calorimeter - W_calorimeter = 0 Then, U_system = -U_surroundings and because no work is done, q_system = -q_surroundings thus... **m_steelc_steelΔT +m_oxygenc_oxygenΔT = -m_waterc_waterΔT**

Answer 97

- only partially dissociate in aqueous solutions

Answer 98

**- The charge can be listed as a Roman numeral following the name of the element** _Examples_ Fe²⁺is Iron(II) and Fe³⁺is Iron(III) Cu+ is Copper(I) and Cu2+ is Copper (II) - The endings *-ous* and *-ic* can be added to the roof ot the Latin name of the element, to respresent ions with lesser and greater charge, respectively _Examples_ Fe²⁺is Ferrous and Fe³⁺is Ferric Cu+ is Cuprous and Cu2+ is Cupric

Answer 99

- Also know as ionization potential - The energy required to remove an electron rom a gaseous species - Always requires the input of heat (an endothermic process) - Trend: ionization energy increases from left to right across a period and from bottom to top in a group

Answer 100

- States that the rate of a reaction is proportional to the number of collisions per second beween reacting molecules - Also suggests, however, that not all collisions result in a chemical collision - Effective collision (one that leads to the formation of products) only occurs if the molecules collide with each other int he correct orientation and with sufficient energy to break their existing bonds and form new ones - Minimum energy of collision necesary for a reaction to take place is called the activation energy (E_a)

Answer 101

- The enthalphy required to produce one mole of a compound from its elements in their standard states - Remember: standard state refers to the most stable phyiscal sate of an element or compound at 298K and 1 atm Symbol: ΔH°_f

Answer 102

- the empirical formula of any ionic or covalent network solid compound used as an independent entity for stoichiometric calculations. It is the lowest whole number ratio of ions represented in an ionic compound - This is because no molecule actually exits, because of the way in which the oppositely charges ions arrange themselves in a three dimension shape Example: NaCl and the lattice it forms - Since no molecule exits, molecular weight is not possible; thus, the term **formula weight** is used instead

Answer 103

- A measure of concentration in _equivalents/L_ **- Molarity = Normality/n** Example: - In a 1N solution of HCl, the molarity of HCl is 1M because HCl is monoprotic - In a 1N solution of H₂CO₃, the molarity of H₂CO₃ is 0.5 M because H₂CO₃ is diprotic

Answer 104

- A special type of galvanic cell, however, the electrodes are chemically identical - Thus, current is generated as a function of the concentration gradient established between the two solutions surrounding the electrodes

Answer 105

- Refer to either non-integer orders (fractions) (also known as **broken-order**) - or refer to reactions with rate orders that vary over the course of a reaction

Answer 106

- A reaction that proceeds in one direction only - The reaction goes to completion and the maximum amount of product formed is determined by the amount of the limiting reagent initially present

Answer 107

Rate Law: rate = k [A]^x [B]^y To figure out B, we see that a doubling in B leads to a 4 fold change in the rate, thus 2^y= 4, so y=2 To figure out A, we see that a doubling in A, doubles the rate, thus 2^x= 2, so x=1 Thus, we have a rate law of: k [A]¹ [B]² To figue out k, take the data and fill in the rate law: 2.0M/s = k [1.00M] [1.00M] so k= 2.0M^-2S^-1

Answer 108

- Atom is in an excited state when at least one electron has moved to a subshell of higher than normal energy ## Footnote - If electron was promoted to an orbit with a larger radius (higher energy), the atom is in the excited state

Answer 109

E = hf h: Planck’s constant; 6.626 × 10⁻³⁴ J·s f : frequency of the radiation

Answer 110

Conjugate acid: the acid that is formed when a base gains a proton Conjugate base: the base that is formed when an acid loses a proton Example: HCO₃^- (aq) + H₂O (l) ⇔ CO₃^2-(aq) + H₃O⁺ (aq) CO₃^2-: conjugate base of HCO₃^- (and now a weak acid) H₃O⁺ : conjugate acid of H₂O (and now a weak base)

Answer 111

- At constant pressure, the volume of a gas is proprtional to its aboslute temperature, expressed in Kelvins V/T= k or V₁/T₁= V₂/T₂

Answer 112

Chiral: asymmetric in such a way that the structure and its mirror image are not superimposable Achiral: A molecule is achiral if it is superimposable on its mirror image.

Answer 113

Dipole moment: A vector quantity which desctibes the separative of positive and negative charges in a polar bond **p=qd** p: dipole moment q: magnitude of the charge d: displacement vector separating the two partial charges

Answer 114

- Draw the Lewis dot structure of the molecule - Count the total number of bonding and nonbonding electron pairs in the valence shell of the central atom - Arrange the electron paris around the central atom so they are as far apart as possible

Answer 115

- To determine the emf of the cell under non-standard conditions **E_cell = E°_cell - (RT/nF) lnQ** E°_cell: emf of the cell under standard conditions R: ideal gas constant T: temrperature in Kelvins Q: reaction quotient for the reaction in If we assume T= 298 K then... **E_cell = E°_cell - (0.0592/n) logQ**

Answer 116

- Accounts for vapor pressure depression caused by solutes in a solution; as a solute is added to a solvent, the vapor pressure of the solvent decreases proportionally - Only holds when the attraction between the different components of the mixture is equal to the attraction between the molces of any one component in its own state P_A= X_AP_A° P_A: vapor pressure of solvent A when solutes are present X_A: mole fraction of solvent A in the solution P_A°= vapor pressure of solvent A in its pure state Example: What is the change in vapor pressure when 180g glyceraldehyde (C₃H₆O₃) are added to 0.18L of water at 100°C? - The density of water at 100C is about 1g/mL and the vapor pressure of water at the same temperature is 1atm because this is the boiling point of water - Mole fraction of glyceraldehyde = 180g x 1mol/92 g = 2 - Mole fraction of water = 0.18L x 1mol/18g = 1L P_A= (0.83)(1) = 0.83 Change in vapor pressure is 1atm - 0.83 atm = 0.17atm

Answer 117

- Known as the nonrepresentative elemetns - Include the transition elements, which have valence electrons in the s and d subshells - Also include the lathanide and actinide series, which have valence electrons in the s and f subshells

Answer 118

Bond length: the average distance between the two nuclei off the atoms in a bond - As the number of shared electrons pairs increases, the two atoms are pulled closer together, resulting in a decreased bond length - Thus, for a given pair of atoms, a triple bond is shorter than a double bond, which is shorter than a single bond

Answer 119

- Because each element can have its electrons excited to a different set of distinct energy levels, each possesses a unique atomic emission spectrum, which can be used as a fingerprint for the element-- this is the atomic emission spectrum - This is how we identify the components of a star

Answer 120

Maximum number of electrons within a subshell = **4l + 2**

Answer 121

Given A_mB_n ⇔ mAⁿ⁺ (aq) + nB^m- (aq) K_sp = [Aⁿ⁺]^m[B^m-]ⁿ Like all other equilibrium constants, the solubility equilibrium is temperature dependent Example: The molar solubility of Fe(OH)₃ isn an aqueous solution is 4 x 10^-10 mol/L. The dissociation reaction is thus: Fe(OH)₃ ⇔ Fe3+ (aq) + 3OH^- The Ksp for this reaction is: [Fe³⁺] [OH^-]³ = Ksp = [x][3x³]

Answer 122

- Stard free energy of a a reaction is the free energy change thar occurs when the reaction is carried out unders standard state condtitions, (T=298 K and P=1atm) ΔG°_rxn = ΣΔG°_{f, products}- ΣΔG°_{f, reactants}

Answer 123

- The resulting ions are named by adding the word hydrogen or dihydrogen to the front of the anion's name - the older method uses the prefix bi- to indicate the addition of a single hydrogen ion _Example_ HCO₃^-is hydrogen carbonate or bicarbonate HSO₄^-is hydrogen sulfate H₂PO₄^-is dihydrogen phosphate

Answer 124

- The measure of the attractive force that an atom will exert on an electron in a chemical bond - The greater the elctronegativity of an atom, the more it attracts electrons within a bound - The lower the ionization energy, the lower the electronegativity; the higher the ionization energy, the higher the electronegativity **- Electronegativity increases across a period from left to right** **- Decreases in a group from top to bottom**

Answer 125

p=m/V = PM/RT

Answer 126

- A reaction in which the rate of formation of product C is independent of changes in the concentrations of any of the reactants, A and B - Have a constant reaction reate equal to the rate constant, l rate=k [A]⁰[B]⁰ = k - Remember: k is a product of temperature, or by adding a catalyst and changing E_a, so it is possible to change the rate of a zero-order reaction by changing these factors

Answer 127

States that in a chemical solution, if the concentration of any one of the ions is increased, then, some of the ions in excess should be removed from solution, by combining with the oppositely charged ions Example: If a salt, such as CaF₂ is dissolved into water alrady containing Ca²⁺ ions (from some other salt, perhaps CaCl₂), the solution will dissolve less CaF₂ than would an euqal mount of pure water

Answer 128

- Highly reactive nonmetals with 7 valence electrons; desperate to complete their octet by gaining an electron - Group VIIA or Group 17 - Due to their high electronegativities and electron affinities, are especially reactive toward the alkali and alkaline earth metals - Not found naturally in their elemental state bur rather as ions (halides) or diatomic molecules

Answer 129

- the minimum pressure which needs to be applied to a solution to prevent the inward flow of its pure solvent across a semipermeable membrane Π= iMRT Π: osmotic pressure i: van't Hoff factor M: molarity of the solution R: the ideal gas constant T: temperature

Answer 130

Dichromate

Answer 131

- A system which can exchange energy (heat and work) but not matter with the surroundings Example: steam radiator

Answer 132

- The (n + l) rule can be used to rank subshells by increasing energy. - This rule states that the lower the sum of the values of the first and second quantum numbers (n + l), the lower the energy of the subshell. - If two subshells possess the same (n + l) value, the subshell with the lower n value has a lower energy and will fill with electrons first.

Answer 133

A species that donates hydrogen ions (H⁺)

Answer 134

- Energy spontaneously disperses from being localized to being spread out of it is not hindered to doing so - This is basically entropy - Examples: hot tea cools down, by the thermal energy in the hot spreading spreading out to the cooler air around it

Answer 135

Bohr assumed that the hydrogen atom consisted of a central proton around which an electron traveled in a circular orbit. He postulated that the centripetal force acting on the electron as it revolved around the nucleus was created by the electrostatic force between the positively charged proton and the negatively charged electron

Answer 136

- The emf correspond to the voltage or electrical potential difference of the cell - If the emf is positive, the cell is able to release energy (ΔG \< 0), which means its spontaneous - If the emf is negative, the cell must absorb energy (ΔG \< 0), which means its nonspontaneous

Answer 137

- A solution in which the solvent is water - Symbolized by (aq)

Answer 138

- Releases a photon of energy - The electromagnetic energy of these photons can be determined by E=hc/λ h: Planck's constant c: speed of light in a vacuum (3.00 x 10⁸m/s) λ: wavelength of the radiation

Answer 139

- Also called semimetals - Share some characteristics with both metals and nonmetals - Atomic level: electronegativities and ionization energy of the metalloids lie between metals and non metals - Their physical properties, such as densities, melting points, and boiling points, vary widely and can be combinations of metallic and nonmetallic characterisics - Reactivities of metalloids dependent on the elements with which they are reacting

Answer 140

- a quantity of any substance (atoms, molecules, etc.) equal to the number of particles thar are found in 12 grams of Carbon-12 - The number of particles found in this is Avogadro's Number, 6.022 x 10²³particles

Answer 141

- The energy dissipated by a gaseous species when it gains an electron - An exothermic process - Halogens are most "greedy" when it comes to this, as one electron will allow them to achieve a noble gas configuration Note: As this is an exothermic process, ΔHrxn is negative, but the electron affinity is positive (for example, acquisition of one electron releases 200kJ/mol, so the ΔHrxn= - 200kJ/mol, but the electron affinity is 200kJ/mol

Answer 142

- When molecules collide with energy equal to or greater than activation energy, they form a transition state in which the old bonds are weakened and the new bonds begin to form - The transition state, also called the activated complex, has greater energy than both the reactants and the products

Answer 143

- Represents a hypotheical gas with molecules that have no intermolecular forces and that occupy no volume - Real gases delviate from this ideal behavior at high pressures (low volumes) and low temperatures, but many compressed gases demonstrate behavior that is close to ideal

Answer 144

reactions that involve the transfer of electrons from one chemical species to another

Answer 145

- Atoms that engage in ionic bonding - This arrangement maximizes the attractive forces between oppositely charged ions and minimizes the repulsive forces between similarly charged ions

Answer 146

- This is the temperature and pressure at which there is no distinction between the liquid and gas phases - The fluids beyond this point are called _supercritical fluids_ - The heat of vaporiztion at this point and for all temperatures and pressures above the critical point values is zero - Logic behind this: as a liquid is heated in a closed system, its density decreases and the density of the vapor sitting above it increases

Answer 147

- If only the wire were provided for electron flow, the reaction would soon stop because an excess positive charge would build up on the anode, and an excessive negative charge with build up on the cathode - Eventually, the excessive charge accumulation woudl provide a countervoltage large enough to prevent the oxidation-reduction reaction from taking place and the current would cease - This gradient is dissipated by the salt bridge, which permits the exchange of cations or anions - The salt bridge contains an inert electrolyte, ususally KCl or NH4NO3, which contains ions that will not react with the electrodes or with the ions

Answer 148

- Can refer to either the amount of a product predicted (**theoretical yield**) or the amount of a producted actually obtained (**raw or actual yield**) when a reaction is carried out Percent Yield = Actual Yield/ Theoretical Yield x 100%

Answer 149

System: the matter that is being observed; the total amount of reactants and products in a chemical solution, the amount of solute and solvent used to create a solution or the amount of gas in a balloon Surroundings: everythig outside the system

Answer 150

- A single reactant breaks down into two or more products, usually as a result of high heating, high-frequency radiation, or electrolyis Example: 2HgO (s) → 2Hg (l) + O₂ (g) - Occurs when heat is applied to HgO

Answer 151

- First, balance the elements which appear once on each side of the reaction - Repeat this, until there are no more elements that only appear once on each side - Then attack the others; at this point, it's ok to have fractions - Then, make all the fractions into whole numbers and check your work

Answer 152

- Group IIA or Group 2 - Share most of the characteristics of the alkali metals, except that they have a slightly higher Zeff, thus slightly smaller radii - They have two electrons in their valence shell, both of which can be easily removed to form divalent cations

Answer 153

pOH= -log[OH^-] = log (1/OH^-])

Answer 154

- A specific type of double-displacement reaction in which an acids reacts with a base to product a salt (and, usually, water) Example: HCl (aq) + NaOH (aq) → NaCl (aq) + H₂O (l)

Answer 155

ΔG= negative, the reaction is spontaneous ΔG = positive, the reaction is nonspontaneous ΔG= 0, the system in a state of equilibrium and ΔH= TΔS

Answer 156

The reaction quotient serves as a quantitative evaluation of how far the reaction has proceeded toward the equilibrium. **Q= [C]c[D]d/ [A]a[B]b** Q in relation to K_eq tells us about how far the reaction has proceeded

Answer 157

Acid equivalent: equal to one mole of H⁺ ions Base equivalent: eqal to one mole of OH^-ions Polyvalent: each mole of acid or base liberates more than one acid or base equivalent

Answer 158

- States that the energy of the emitted photon corresponds to the difference in energy between the higher-energy initial state and the lower-energy final state

Answer 159

P₁V₁/T₁= P₂V₂/T₂

Answer 160

- Group VIA or Group 16 - An eclectic group of nonmetals and metalloids - Not as reactive as the halogens, they are crucial for normal biological functioning - They have six electrons in their valence shell - Due to their proximity to the metalloids, generally have small atomic radii and large ionic radii - Important ones: Oxygen, sulfur, selenium

Answer 161

A species that accepts hydrogen ions (H+)

Answer 162

1. Write the equilibrium reaction CH₃COOH (aq) + H₂O (l) ⇔ H₃O⁺ (aq) + CH₃COO^- (aq) K_a= [H₃O⁺] [CH₃COO^-] / [CH₃COOH] 2. Recognize that acetic acid is a weak acid so the concentration of CH3COOH at equilibrium is equal to initial concentration, 2.0M, minus the ammount dissociated, x - Likeweise, [H₃O⁺] = [CH₃COO^-] = x because each molecule of CH3COOH dissociates into one of each 3. Write out the equation K_a= [x] [x] / [2.0M - x] = 1.8 x 10^-5 4. Since x is very small, since we are working with a weak acid, ignore it on the bottom K_a= [x] [x] / [2.0M] = 1.8 x 10^-5 5. Solve for x x²= 3.6 x 10^-5or 36 x 10^-6(to make square rooting it easier) x= 6 x 10^-3M

Answer 163

- Changing the temprature of a system will cause the change in the K_eq(and not the Qc or Qp as with changes in concentration and pressure) - If a reaction is endothermic (ΔH \> 0), heat functions as a reactant - If a reaction is exothermic (ΔH \< 0), heat functions as a product

Answer 164

- for nearly all reactions, the reaction rate will increase as the temperature increases - the temperature of a substance is a measure of the particles' average kinetic energy, increasing the temperature increases the average kinetic enregy of the molecules; consequently, the prorportion of reactants gaining enough energy to surpass E_a increases with higher temperature

Answer 165

States that all gases at constant temperature and pressure occupy volumes that are directly proportional to the number of moles of gas present - Equal amounts of all gases at the same temperature and pressure will occupy equal volumes n/V= k (a constant) or n1/V1=n₂/V₂ Note: this implies: as the numbr of moles of a gas increases, the volume increases in direct proportion

Answer 166

- a measure of the spontaneous dispersal of energy at a specific temperature: how much enery is spread out or how widely energy becomes spread out ΔS = Q_rev/T ΔS: change in etropy Qrev: heat that is gained or lost in a reversible process T: temperature in kelvin Units: J/mol x K

Answer 167

- A reaction which has two or more reactants forming one product Example: 2H₂ (g) + O₂ (g) →2H₂O (g) - Combination reactions have more reactants than products

Answer 168

- A state function; a change in Gibbs free energy, ΔG, is a measure of the change in enthalpy and change in entropy - indicates whether a reaction is spontaneous or non-spontaneous ΔG= ΔH- TΔS Mneumonic: **G**oldfish are (equals sign) **H**orrible without (minus sign) **T**artar **S**auce

Answer 169

1. Gases are made up of particles with volumes that are negligible compared to the container volume 2. Gas atoms or molecules exhibit no internmolecular attractions or repulsions 3. Gas particles are in continuous, random motion, undergoing collisions with other particles and the container walls 4. Collisions between any two gas particles (or between particles and the container walls) are elastic, meaning that there is conservation of both momentum and kinetic energy 5. The average kinetic energy of gas particles is proportional to the absolute temperature of the gas (in kelvins) and it is the same for all gases at a given temperature, irrespective of chemical identity or atomic mass

Answer 170

It=nF where n is the moles of electrons and F is Faraday’s constant. Use 100,000 or 10⁵ Coulomb/mole of electrons for any calculation. (C/s)(s)=(mol e⁻)(C/mol e⁻) Example: A current is passed through a Ga(NO₃)₃ solution for 1.5 hours, and after this time period the mass of metal produced was 6.3 grams. What is the current, in amperes, that is required to produce such an amount of gallium? Solution: Image

Answer 171

- The maximum amount of a substance that can be dissolved in a particular solvent at a given time - When this maximum amount of solute has been added, the solution is _saturated_

Answer 172

ΔH_fusion (heat of fusion): when undergoing a phase change, transitioning across the solid-liquid boundary ΔH_vap (heat of vaporization): when undergoing a phase change, transitioning across the liquid-gas boundary **q=mL** m: mass L: latent heat, the enthalpy for an isothermal process

Answer 173

- A technique used to measure transferred heat Example: a coffee-cup calorimeter - An insulated contained covered with a lid and filled with a solution in which a reaction or some physical process is occurring; the incident pressure, which is the atmospheric pressure, remains constant throughout the process and teh tmerpature can be measured as the reaction progresses - There should be sufficient thermal insulation (such as Styrofoam) to ensure that the heat being measured is an accurate representation of the reaction, without gain or loss of heat to the environment

Answer 174

1.7 on the Pauling scale

Answer 175

Equivalents = mass of a gompound (g) / gram equivalent weight (g)

Answer 176

- The greater an atom's Z_effor the closer the valence electrons are to the nucleus, the more tightly bound they are - This makes it more difficult to remove one or more electrons, increasing the ionization energy - Thus, higher Z_eff, higher inoization energy

Answer 177

- A state function, which describes heat changes at constant pressure - We can calculate the change in enthalpy (ΔH) for a system that has undergone a process, for example, a chemical reaction, by comparing the final state of enthalpy compared to the initial state, _irrespective of the path taken_ ΔHrxn = H_products - H_reactants ΔH_rxn\>0; endothermic process ΔH_rxn \<0; exothermic process

Answer 178

Permanganate

Answer 179

- As an amphoteric compound, water can react with itself (autoionization) H₂O (l) + H₂O (l) ⇔ H₃O⁺(aq) + OH^-(aq) K_w= [H₃O⁺][OH^-] = 10^-14 at 25°C - Each mole of water that autoionizes produces one mole of hydrogen (or hydronium) ions and hydroxide ions, so the concentrations of hydrogen ions and hydroxide ions are always equal in pure water at equilibrium [H₃O⁺] and [OH^-] = 10^-7M

Answer 180

- Any element in period 3 or greater can hold more than eight electrons - Includes: phosphous (10), sulfur (12), chlorine (14) and many more

Answer 181

- Also known as an isovolumetric process, experience no change in volume - Because the gas neither expands nor compresses, no work is performed in such a process (W=0) If W=0, then , ΔU = Q - 0 and thus, **ΔU = Q**

Answer 182

- Can function as both galvanic and electrolytic

Answer 183

- A second-orer reaction has a rate that is proportional to either the concentrations of two reactants or to the square of the concentration of a single reaction - Second-order rate law often suggests a phyiscal collision between two reactant molecules, especially if the rate rate law is first-order with respect ot each of the two reactants rate=k [A]¹ [B]¹ or rate=k [A]² or rate=k [B]²

Answer 184

Electrochemical cell that derives electrical energy from spontaneous redox reactions taking place within the cell. It generally consists of two different metals connected by a salt bridge, or individual half-cells separated by a porous membrane. ΔG \<0 Ecell or emf = positive

Answer 185

- ## Footnote - Negatively charged ions (anions) have additional electrons that fill according to the same rules as above; for example, if fluorine’s electron configuration is [He] 2s²2p⁵, then F^– is [He] 2s²2p⁶ ^- Positively charged ions (cations) are a bit more complicated: start with the neutral atom, and remove electrons from the subshells with the highest value for n first. If multiple subshells are tied for the highest n value, then electrons are removed from the subshell with the highest l value among these Example: What is the electron configuration of Fe3+? Solution: The electron configuration of iron is [Ar] 4s²3d⁶. Electrons are removed from the 4s subshell before the 3d subshell because it has a higher principal quantum number. Therefore, Fe3+ has a configuration of [Ar] 3d⁵, not [Ar] 4s²3d³.

Answer 186

- A type of intermolecular force - While the bonding electrons in a non-polar covalent bond may appear to be shared equally between two atoms, at any point in time, they will actually be located randomly throughout the orbital - Thus, in a given moment, the electron density may be unequally distributed between two forces - This results in a rapid polarization and coutnerpolarization of the electron cloud and the formation of a short-lived dipole moment - These dipoles interact with the electron cloud densities of neighboring compounds, inducing more dipoles in these compounds - A type of Van der Waals force - This is the weakest force because they are the result of induced dipoles that change and shift moment to moment and do not extend over long distances and are only signficiant when molcules are in close proximity

Answer 187

If the equilibrium constant for a reaction in one direction is K_eq, the equilibrium constant for the reverse reaction is 1/K_eq

Answer 188

- provides a rate constant for a reaction k: rate constant of a reaction A: the frequency factor (how often molecules in a certain reaction collide) E_a: activation energy of the reaction R: ideal gas constant T: temperature in _kelvin_ _Note: the equation is less important than the relationships between variables_

Answer 189

Moles = Mass of sample (g) / Molar mass (g/mol)

Answer 190

- Absorb light - Higher potential - Excited - Distant (from the nucleus)

Answer 191

M_iV_i=M_fV_f M: molarity

Answer 192

q = mcΔT q: heat m: mass c: specific heat ΔT: change in temperature (in celsius or kelvins)

Answer 193

an abstract one-dimensional coordinate which represents progress along a reaction pathway, tracing the reaction from reactants to products

Answer 194

PV=nRT P: pressure V: volume n: number of moles T: temperature R: 8.21 x 10-2 L atm/mol K

Answer 195

**rate = k [A]^x [B]^y** **Note: This is the _rate law_** k: the reaction rate coefficient or rate constant x and y: orders of the reaction, x is the order with respect to A, y is the order with respect to B _- the overall order of the reaction is the sum of x an y_ Units: molarity per second

Answer 196

**Chromium (and other elements in its group)** - Chromium (Z = 24) should have the electron configuration [Ar] 4s²3d⁴ according to the rules established earlier. However, moving one electron from the 4s subshell to the 3d subshell allows the 3d subshell to be half-filled: [Ar] 4s¹3d⁵ (remember that s subshells can hold two electrons and d subshells can hold ten). While moving the 4s electron up to the 3d-orbital is energetically unfavorable, the extra stability from making the 3d subshell half-filled outweighs that cost. **Copper (and other elements in its group)** - Copper (Z = 29) has the electron configuration [Ar] 4s¹3d¹⁰, rather than [Ar] 4s²3d⁹; a full d subshell outweighs the cost of moving an electron out of the 4s subshell.

Answer 197

An equivalent is the amount of a substance needed to do one of the following: - react with or supply one mole of hydrogen ions (H+) in an acid–base reaction - react with or supply one mole of electrons in a redox reaction Example: One mole of HCl can donate one mole of H⁺ to a solution (one equivalent), one mole of H₂SO₄ can donate two moles of H⁺ to a solution (two equivalents) and one mole of H₃PO₄ can donate three moles of H⁺ to a solution (three equivalents)

Answer 198

- A substance will will dissociate to form an excess of H⁺

Answer 199

Empirical formula: gives the simplest whole-number ratio of the elements in the compound Molecular formula: gives the exact number of atoms of each element in the compound and is a multiple of the empiric formula _Example:_ - Empiric formula for benzene: CH - Molecular formula for benzene: C₆H₆

Answer 200

- The movement of molecules from high concentration to low concentration through a medium - The kinetic molecular theory of gases predicts that heavier gases diffuse more slowly than lighter ones because of their different average spepeds; because all gas particles have the same average kinetic energy at the same time, it must be true that particles with greater mass travel at slowe average speed **r1/r2 = √M₂/M₁** r: rate of diffusion M: molar masses

Answer 201

- sigma (σ) bonds occur when orbitals overlap head-to-head; these bonds allow for free rotation about their axes becuase the electron density of the bondign orbital is a single linear accumulation between the atomic nuclei - pi (π) bonds occur when orbitals overlap in such a way that there are two parallel cloud densisites; do not allow for free rotation between the electron densities of the orbitals are parallel and cannot be twisted in such a way that allows continuous overlapping of the clouds of electron densities

Answer 202

- Noble gases would be predicted to have the highest electron affinities, according to the trend, but they actually have electron affinities on the order of zero because they already possess a stable octete and cannot readily accept any electrons - Halogens are most "greedy" when it comes to this, as one electron will allow them to achieve a noble gas configuration

Answer 203

- A type of covalent bond in which the shared electrons are contributed by only one of the two atoms

Answer 204

Charge: 1.6 × 10⁻¹⁹ C Mass: 1 amu

Answer 205

- Rules in order to determine ionic radii: Metals lose electrons and become positive; nonmetals gain electrons and become negative; metalloids can go in either direction, but tend to follow the trend based on which side of the the metalloid line they follow - Nonmetals close to the metalloid line: these gain electrons while their nuclei maintain the same chage; thus possessing a larger nuclei than their counterparts closer to Group VIIIA - Metals close to the metalloid line: lose electrons, but nuclei is the same, so ionic radii is smaller

Answer 206

- A first-order reaction has a rate that is directly proportional to only one reactant, such that a doubling of that reactant results in a doubling of the rate formation of the product rate=k [A]¹ or rate=[B]¹

Answer 207

- Bond energy is the energy required to break a bond by separating its components into their isolated, gaseous, atomic states - The greater the number of electrons shared between the atoms nuclei, the more energy is reqeuired to break the bonds holding the atoms together - Thus, triple bonds have the greatest bond energy and single bonds have the lowest bond energy

Answer 208

**Weakest** - Dispersion forces or London forces - dipole-dipole interactions - hydrogen bonding **Strongest**

Answer 209

- The size of the atomic mass unit is defined as exactly 1/12 the mass of the carbon-12 atom, approximately 1.66 × 10⁻²⁴ g - amu is approximately equal to the mass of a proton or a neutron

Answer 210

- states that in the ground state of an atom or ion, electrons fill atomic orbitals of the lowest available energy levels before occupying higher levels

Answer 211

- Active metals: elements in Groups IA and IIA (Groups 1 and 2) - Very low ionization energies - Do not exist naturally in their neutral forms; they are always found in ionic compounds, minerals or ores - Loss of one or two electrons, from Group 1 and 2, respectively, results in the formation of a stable, filled valence shell

Answer 212

Root-mean-square speed is the measure of the speed of particles in a gas which is most convenient for problem solving within the kinetic theory of gases urms= √(3RT/M) R: ideal gas constant (8.314 J/K mol) T: temperature M: molar mass

Answer 213

- The changes in enthalpy, entropy, and free energy that occur when a reaction takes place under standard conditions Standard enthalphy change: ΔH° Standard entropy change: ΔS° Standard free energy change: ΔG°

Answer 214

- Reactants can undergo two different sets of reactions - At lower temperatures (with smaller heat transfer), a kinetic product is formed - At higher temperatures, with larger heat transfer, a thermodynamic product is formed - The kinetic pathway requires less free energy to reach the transition state, but results in a higher-energy (less stable) product - Note: the free energy that must be added for the kinetic pathway is lower than for the thermodynamic pathway; therefore, the kinetic products often form fatster and are sometimes called "fast" products - The free energy of the thermodynamic products is significatly lower than that of the kinetic product; thermodynamic products are therefore associated with greater stability and with a more negative ΔG than kinetic products

Answer 215

Is one of two stereoisomers that are mirror images of each other that are non-superposable (not identical), much as one's left and right hands are the same except for being reversed along one axis (the hands cannot be made to appear identical simply by reorientation).

Answer 216

- In electronic density, the ideal bond angle is the angle which will be created by the electrons when they are as far away from each other as possible - This is not consistent, as non-bonding pairs are able to exert more repulsion than bonding pairs, because these electrons reside closer to the nucleus - Example: Ammonia and water should have ideal angles of 109.5 degrees - However, because of the non-bonding pairs of electrons, the angles are actually 107 and 104.5 degrees, respectively

Answer 217

- Electronegative elements positioned near an acidic proton increase acid strength by pulling electron density out of the bond holding the acidic proton; this weakes the proton bonding and facilitates dissociation - Thus, acids that have electronegative elements nearedr to acidic hydrogens are stronger than those that do not

Answer 218

- A solution that is able to carry current - The electrical conducitivity an aqueous solutions is governed by the presence of ions in the solution Strong electrolyte: if the solute dissociates completely into its constituent ions Weak electrolytes: ionizes or hydrolyzes incompletely in aqueous solution, and only some of the solute is dissolved into its ionic constituents

Answer 219

- When an electron pair is shared between two atoms, typically nonmetals, that have regularly similar values of electronegativity - The degree to which the pair of electrons is shared equally or unequally between the two atoms determines the degree of polarity in the covalent bond; if its euqal, the bond is nonpolar, if it's not, the bond is polar

Answer 220

ΔU = Q - W ΔU: change in the internal energy of the system Q: the heat added to the sytem W: work done by the system

Answer 221

Thiocyanate

Answer 222

- A type of reaction that involves a fuel, usually a hydrocarbon, and an oxidant (normally oxygen) - In the most common form, these reactants form the two products of carbon dioxide (CO₂) and water (H₂O) Example: CH₄ + 2O₂ → CO₂ + 2H₂O

Answer 223

A homogenous (the same throughout) mixture of two or more substances that combein to form a single phase, usually the liquid phase

Answer 224

- Percent composition of an element (by mass), is the percent of a specific compound that is a made up a given element **Percent composition= (Mass of element in formula/molar mass) x 100%**

Answer 225

- Group IA or Group 1 - Possess most of the classic physical properties of metals, except that their densities are lwoer than those ot ofter metals - Have only one loosely bound electron in their outershell - Low Z^eff, giving them large atomic radii, low ionization energies, low electron affinities and low electronegativies - Easily lose one electron to become a cation - React readily with non-metals

Answer 226

- Enthalphy is equivalent to heat under constant pressure

Answer 227

P_T= P_A+P_B + P_C..... P_A=X_A/P_T Where X_A=moles of gas A/total moles of gas Example: A vessel contains 0.75 mol of nitrogen, 0.2 mol of hydrogen and 0.05 mol of fluoriine at a total pressure of 2.5atm. What is the partial pressure of each gas? X_N2= 0.75mol/1.00mol X_H2= 0.2mol/1.00mol XF2= 0.05mol/1.00mol P_N2= (0.75) (2.5atm)= 1.875atm PH2= (0.2) (2.5atm)= 0.5atm PF₂= (0.05) (2.5atm)= 0.125atm

Answer 228

- States that if stress is applied to a system, the system shifts to relieve that applied stress

Answer 229

- If a molecule has several dipoles, but the molecular geometry of the molecule arranges these dipoles such that they cancel out, the molecule will have polar bonds, but be a non-polar molecule, overall - However, in the same molecular arrangement, another molecule may be polar Example: CCl₄ vs CHCl₃

Answer 230

The electrostatic attraction between the valence shell electrons and the nucleus **- For elements in the same period, Zeff increases from left to right** - As the positivity of the nucleus increases, the electrons surrounding the nucleus, including those in the valence shell, experience a stronger electrostatic pull **- For elements in the same group, the Zeff stays relatively consistent**

Answer 231

- A system which cannot exchange energy (heat or work) or matter the surroundings - Example: bomb calorimeter

Answer 232

- Atoms that share an atomic number but have different mass numbers - Atomic number: protons - Mass number: protons + neutrons

Answer 233

- refers to the shorthand representation of the principal and azimuthal quantum number - The principal quantum number remains a number, but the azimuthal quantum number is designated by a letter: - the l = 0 subshell is called s - the l = 1 subshell is called p - the l = 2 subshell is called d - the l = 3 subshell is called f - Thus, an electron in the shell n = 4 and subshell l = 2 is said to be in the 4d subshell

Answer 234

- The second quantum number refers to the shape and number of subshells within a given principal energy level (shell) - designated by the letter: l - the range of possible values for l is 0 to (n – 1) Hint: A way to remember this relationship is that the n-value also tells you the number of possible subshells; if n=1, then there is only 1 subshell (0); if n=2, then there are two subshells, 0 and 1

Answer 235

Cr₂O₇^2-

Answer 236

L= nh/2π n: principal quantum number (any positive integer) h: Planck's constant - Because the only variable number is the principal number, the change in angular moment occurs only in discrete amounts

Answer 237

**ΔG°rxn = -RTlnK_eq** R: ideal gas constant T: temperature in kelvins K_eq: equilibrium constant - This applies when the reaction is in equilibrium - However, once the reaction begins, the standard state conditions (specifically 1M solutions) no longer apply **ΔGrxn = ΔG°rxn +RTlnQ = RTln Q/K_eq**

Answer 238

equal to the number of protons found in an atom of that element - Acts as a unique identifier of that element

Answer 239

- When a weak acid is placed in aqueous solution, it will only partially dissociate; thus, there will be an equilibrium between the associated and dissociated components HA (aq) + H₂O (l) ⇔ H₃O⁺ (aq) + A^- (aq) **K_a= [H₃O⁺] [A^-] / [HA]** - The smaller the K_a, the weaker the acid and the less it will dissociate - K_a \< 1 is considered a "weak acid"

Answer 240

- The component of the solution that remains in the same phase after mixing - If the two components are already in the same phase (for example, a solution of two liquids), the solvent is the component present in greater quantity) - If they are in the same phase and equal quantity, the component that is more commonly used as a solvent is the solvent

Answer 241

mass of solute/mass of solution x 100% Example: What is the percent composition by mass of a salt water solution if 100g f the solution contains 20g of salt? mass of solute/mass of solution x 100% = 20g/100g x 100% = 20% NaCl solution

Answer 242

K_{a, acid}x K_{b, conjugate base} = K_w = 10^-14 K_{a, base}x K_{b, conjugate acid} = K_w = 10^-14 - Thus, if K_a is large, then K_b is small and vice-versa - Example: a strong acid like HCl (K_a approaching infinity) will produce a weak conjugate base like Cl^- - a weak acid or base tends to have conjugates that are also weak

Answer 243

- Occurs when an atom or ion in a compound is replaced by an atom or ion of another compound Example: Cu (s) + AgNO₃ (aq) → Ag (s) + CuNO₃ (aq) - Single displacement reactions are often further classified as oxidation-reduction reactions

Answer 244

- A number of “things” (atoms, ions, molecules) equal to Avogadro’s number: N_A = 6.02 × 10²³ Example: the atomic weight of carbon is 12g/mol which means that the average carbon atom has a mass of 12.0 amu (carbon-12 is far more abundant than carbon-13 or carbon-14), and 6.02 × 10²³ carbon atoms have a combined mass of 12.0 grams.

Answer 245

- The triple point is the temperature and pressure at which the three phases (gas, liquid, solid) exist in equilibrium

Answer 246

- Noble gases (Group VIIIA or 18) are the least likely to give up electrons - They have a stable electron configuration and are unwilling to disrupt that stability by giving up an electron - Thus, they have the highest ionization energies

Answer 247

- Because of the strength of the electrostatic force between the ionic constiuents of the compound, ionic compounds have very high melting and boiling points - Many ionic compounds dissolve readily in water and other polar solvents - Are, in the molten state, good conductors of electricity - In the solid state, form a crystalline lattice, consisting of positive and negative ions

Answer 248

- If we percieve an object as a particualr color, it is because that color is reflected by the object - if an object absorbds a given color of light and reflects all others, our brain mixes these subtraction frequencies and we perceieve the complementary color of the frequency that was absorbed

Answer 249

pH= -log[H+] = log (1/[H+])

Answer 250

- Reactions in n which the reaction proceeds forward and revese - Usually do not proceed to completion because the products can react to reform the reactants - When in a close system and no reactants or products are added or removed, the system will eventually settle into a state in which the rate of the forward reaction equals the rate of the revere reaction (dynamic equilibrium)

Answer 251

Difference of 0.5 - 1.7 on the Pauling Scale

Answer 252

An electron pair donor

Answer 253

Exothermic: - When the new interactions are stronger than the orignal ones, the solvation is exothermic, and the process is favored at lower temperatures (think of Le Chatlier's principle) Endothermic: - When the new interactions are weaker than the original ones, solvation is endothermic and the process if favored at high temperatures - Most dissolutions are of this type

Answer 254

- Enthalpy is a state function and is a property of the equilibrium state, so the pathway taken for a process is irrelevant to the change in enthalpy from one equilibrium to another - Hess's Law: States that enthalphy changes of reactions are additive

Answer 255

- When the overall strength of the new interactions is approximately equal to the overall strength of the original interactions - In this case, the overall enthalpy change for the dissolution is close to zero - These types of solutions _approximate an ideal solution_, for which the enthalphy of dissolution is equal to zero

Answer 256

- The number of shared electron paris between two atoms - A single bond has a bond order of one - A double bond has a bond order of two - A triple bond has a bond order of three

Answer 257

**periods: rows** **groups or families: columns** - seven periods, representing the principal quantum numbers n = 1 through n = 7 for the s- and p-block elements; each period is filled sequentially, and each element in a given period has one more proton and one more electron than the element to its left (in their neutral states - Groups contain elements that have the same electronic configuration in their valence shell and share similar chemical properties

Answer 258

2n² - n: principle quantum number

Answer 259

If -log (n x 10^-m) , we can estimate that the p-value is approximately m - 0.n Example: if the K_a of an acid is 1.8 x 10^-5, what it its pK_a? We can estimate that the pKa ≈ 5- 0.18 = 4.82 (actual value= 4.74)

Answer 260

No two electrons in a given atom can possess the same set of four quantum numbers (n, l, m_l, m_s)

Answer 261

**Found** - On the left side and in the middle of the periodic table **Include** - Include the active metals, the transition metals and the lanthanide and actinide series of elements **Characteristics** - Lustrous (shiny) solids (except mercury) under standard conditions - Have high melting points - Have high densities - Have the ability to be deformed without breaking: malleable and ductile - Atomic level: low effective nuclear change, low electronegativity, large atomic radius, small ionic radius, low ionization energy and low electron affinity

General Chemistry Flashcards

(304 cards)