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chemsitry > Alevel Revision > Flashcards

Alevel Revision Flashcards

1
Q
  • What is mass/ atomic number?
  • What are isotopes ?
  • Explain the The principles of a simple time of flight (TOF) mass spectrometer, limited to ionisation, acceleration to give all ions constant kinetic energy, ion drift, ion detection, data analysis?
  • What is the purpose of mass spectrometry ?
  • How do you interpret simple mass spectra of elements And calculate relative atomic mass from isotopic abundance, limited to mononuclear ions?
A
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2
Q

Explain the electron configurations including all the sun shells
define first ionisation energy
write equations for first and successive ionisation energies
explain how first and successive ionisation energies in Period 3 (Na–Ar) and in Group 2 (Be–Ba) give evidence for electron configuration in sub-shells and in shells.

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3
Q

What is ar and mr

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4
Q

Explain the Avogadro constant
Equation for amount in moles
How to find concentration, volume and amount of substance in a solution.

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5
Q

What is ideal gas equation

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6
Q

What is empirical and molecular formulas what is the relation
How to calculate empirical formula from data giving composition by mass or percentage by mass
How to calculate molecular formula from the empirical formula and relative molecular mass.

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7
Q

How to write a full or ionic equation
What is atom economy
What are the Economic, ethical and environmental advantages for society and for industry of developing chemical processes with a high atom economy. write balanced equations for reactions studied
How to balance equations for unfamiliar reactions
when reactants and products are specified.
Students should be able to use balanced equations to calculate:
masses
volumes of gases
percentage yields
percentage atom economies
concentrations and volumes for reactions in solutions.

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8
Q

What is an ionic bond
How are compound ions formed give examples
How to predict the charge on a simple ion using the position of the element in the Periodic Table
How to construct formulas for ionic compound

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9
Q

What is a covalent and vo ordinate bond
What is metallic bonding

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10
Q

What are the four types of crystal structures give examples

relate the melting point and conductivity of materials to the type of structure and the bonding present
explain the energy changes associated with changes of state
draw diagrams to represent these structures involving specified numbers of particles.

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11
Q

What are bonding pair and lone pair of electrons what causes repulsion
What are the The effect of electron pair repulsion on bond angles

explain the shapes of, and bond angles in, simple molecules and ions with up to six electron pairs (including lone pairs of electrons) surrounding the central atom.

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12
Q

What is electronegative
What is a polar covalent bond and a permanent dipole

How do you use partial charges to show that a bond is polar
explain why some molecules with polar bonds do not have a permanent dipole.

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13
Q

What are the 3 different intermolecular forces how does the melting an boiling point differ
What is the importance of hydrogen bonding in the low density of ice and the anomalous boiling points of compounds.

explain the existence of these forces between familiar and unfamiliar molecules
explain how melting and boiling points are influenced by these intermolecular forces.

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14
Q

What is the definition for enthalpy?
* What is the unites for change in enthalpy?
* What happens during bond braking and forming and what type of reaction is it?
* What is the equation for enthalpy change?

A
  • Enthalpy is the heat energy change measured under constant pressure
  • kj mol -1
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15
Q
  • What is the definition for hess law
  • Describe how to do hess law for enthalpy of formation
  • Describe how to do hess law for enthalpy of combustion
A
  • The enthalpy change is independent to the rout it takes
  • In a question the enthalpy of formation for compounds are given, the second equation that you write at the bottom is the elements the product is formed from.
    write in the given enthalpies and reverse the pos or neg from the second equation to the products side as all the arrows will be pointing toward the smaller equation containing the constituent elements
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16
Q
  • Describe how to do hess law for enthalpy of formation
  • Describe the Hess law for combustion
A
  • In a question n enthalpy of formation for compounds are given, the second equation that you write at the bottom is the elements the product is formed from.
    write in the given enthalpies and reverse the pos or neg from the second equation to the products side as all the arrows will be pointing toward the smaller equation containing the constituent elements
  • when doing combustion reaction the smaller equation at the bottom is going to be co2 and h2o you will have to see the number of carbon and hydrogen in the equation to find the number of co2 and h20 and all the arrows go to the small equation containing h2o and co2
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17
Q
  • Define mean bond enthalpy?
  • What is the difference between mean bond enthalpy and enthalpy in hess law?
A
  • average energy needed to break a bond in a compound
  • Mean bond enthalpies are mean values calculated across a range of compounds containing that bond where as Hess’s law find the actual values of the bond enthalpies in that reaction
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18
Q

define the term activation energy
explain why most collisions do not lead to a reaction.

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19
Q

Explain Maxwell–Boltzmann distribution of molecular energies in gases.

draw and interpret distribution curves for different temperatures.

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20
Q

What is rate of reaction.

What are the qualitative effect of temperature changes on the rate of reaction.

use the Maxwell–Boltzmann distribution to explain why a small temperature increase can lead to a large increase in rate. Required practical 3
Investigation of how the rate of a reaction changes with temperature.

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21
Q

What arrr we the qualitative effect of changes in concentration on collision frequency.

What is the The qualitative effect of a change in the pressure of a gas on collision frequency.
explain how a change in concentration or a change in pressure influences the rate of a reaction.

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22
Q

What is a catalyst

use a Maxwell–Boltzmann distribution to help explain how a catalyst increases the rate of a reaction involving a gas.

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23
Q

What happens to the concentration and rate In a reversible reaction at equilibrium
What is le chatalias principle what is used for
Does catalysts affect position of equilibrium

use Le Chatelier’s principle to predict qualitatively the effect of changes in temperature, pressure and concentration on the position of equilibrium
explain why, for a reversible reaction used in an industrial process, a compromise temperature and pressure may be used.

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24
Q

What is an equilibrium constant equation deduced from and for
Dose concentration of catalyst affectequlibrij
Constant

construct an expression for Kc for a homogeneous system in equilibrium
calculate a value for Kc from the equilibrium concentrations for a homogeneous system at constant temperature
perform calculations involving Kc
predict the qualitative effects of changes of temperature on the value of Kc

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25
Q

What is oxidation and reduction
What are the rules of assigning oxidation states

work out the oxidation state of an element in a compound or ion from the formula
write half-equations identifying the oxidation and reduction processes in redox reactions
combine half-equations to give an overall redox equation.

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26
Q

Define lattice enthalpy formation and dissociation?

A
  • Formation is the enthalpy change when one mole of solid ionic compound is formed from its gasious ions
  • dissociation it is dissociated insead of formed
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27
Q

What in a born hanger cycle is used to find lattice enthalpy?

A
  • enthalpy of formation
  • ionisation enegry
  • enthalpy of atomisation
  • bond enthalpy
  • electron affinity
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28
Q

Define enthalpy of formation
Define ionisation energy?
Define enthalpy of atomisation?
Define bond enthalpy?
Define electron affinity?

A
  • Enthalpy change when one mole of compound is formed from its elements in their standeard state under standard conditions
  • Enthalpy change when one mole of gaseous ions 1+ ions is formed from 1 mole of gaseous atoms
  • Enthalpy change when 1 mole of compound is converted to gaseous ions atoms
  • Enthalpy change when all bonds of the same type in one mole of gaseous molucles are broken
  • Enthalpy cahnge when 1 mole of gaseous 1- ions is formed from 1 mole of geaseous atoms
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29
Q

How do you construct a born barber cycle to find lattice enthalpy?

A

Llattice enthalpy=first electron affinity - first ionisation energy-atomistion enthalpy + enthalpy of formation
take eveythin away exept formation as the arrow on the cycle gose the other way

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30
Q

How can we use lattice enthalpy from experimental values and theoretical value to see if their more ionic or if they have covalent character?

A

If experemntal value is further away from the theoretical vale, it will have more covalent charcteristics as it is more polorised, this means that it will be stronger than the predicted ionic model

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31
Q
  • Define enthalpy change of hydration?
  • Define enthalpy change of solution?
A
  • Enthalpy change when 1 mole of aqueous ions is formed from 1 mole of gaseous ions
  • Enthalpy change when 1 mole of solute is dissolved in enough solution that further enthalpy change would not happen
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32
Q

How to draw a born harper cycle using enthalpy of solution, hydration and lattice dissociation enthalpy

A

lattice dissociation enthalpy add enthalpy of hydration, you will be asked to draw a born harber cycle (look up)

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33
Q

Define entropy?
What affects entropy?
What is ment by feasible?
How to find total entropy?
how to entropy of vapourisation?

A
  • The level of disorder
  • The state and number of particles
  • reactions tend towards disoreder so some reaction are just feasible (just happen)
  • total S= S of products -S of reactants
  • Rearranging the Gibbs equation allows us to find the entropy change using the enthalpy change:
    ΔGꝋ = ΔHꝋ – TΔSꝋ = 0
    ΔHꝋ = TΔSꝋ
    ΔSꝋ = ΔHꝋ / T (google the rest)
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34
Q
  • Define gibs free energy change
  • What is the equation for gibs free energy give unites and what should it equal to for the reaction to be feasible
A
  • it preicts if a reaction is feasible or not
  • if it it is less that or equall to 0 the reaction may happen, the equation is ∆G = ∆H – T∆S (enthalpy (j mol-1)- temperature(k) * entropy(J K-1 mol-1))
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35
Q
  • How gibs free energy is affected by a change in temperature
  • If a reaction is feasible how can you calculate temperature?
A
  • exothermic (-∆H) and postive entropy(+∆S)= reaction is feasible at any temperatures
  • endothermic (+∆H) and negtive entropy(-∆S)= reaction is not feasible at any temperatures
  • endothermic (+∆H) and postive entropy(+∆S)= reaction will only be feasible at high temperatures
  • exothermic (-∆H) and negtive entropy(-∆S)= reaction is feasible at low temperatures
  • if a reaction is feasible rearrange to make T subject
    ΔGꝋ = ΔHꝋ – TΔSꝋ = 0
    ΔHꝋ = TΔSꝋ
    ΔSꝋ = ΔHꝋ / T
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36
Q

What is a rate equation describe and explain rate constants and orders
What is the equation for rate constants and what may cause it to vary

define the terms order of reaction and rate constant
perform calculations using the rate equation
explain the qualitative effect of changes in temperature on the rate constant k
perform calculations using the equation k = Ae–Ea/RT
understand that the equation k = Ae–Ea/RT can be rearranged into the form ln k = –Ea /RT + ln A and know how to use this rearranged equation with experimental data to plot a straight line graph with slope –Ea/R

How can orders with respect to reactants can provide information about the mechanism of a reaction.

use concentration–time graphs to deduce the rate of a reaction
use initial concentration–time data to deduce the initial rate of a reaction
use rate–concentration data or graphs to deduce the order (0, 1 or 2) with respect to a reactant
derive the rate equation for a reaction from the orders with respect to each of the reactants
use the orders with respect to reactants to provide information about the rate determining/limiting step of a reaction.

A
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37
Q

What is the The equilibrium constant Kp how is it calculated

derive partial pressure from mole fraction and total pressure
construct an expression for Kp for a homogeneous system in equilibrium
perform calculations involving Kp
predict the qualitative effects of changes in temperature and pressure on the position of equilibrium
predict the qualitative effects of changes in temperature on the value of Kp
understand that, whilst a catalyst can affect the rate of attainment of an equilibrium, it does not affect the value of the equilibrium constant

A
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38
Q

what is the relation of partal pressure to total pressure
what is mole reaction
equation for partial pressure
equilibrium constant
what affect kp

A

partial pressire a+B+C=total pressure
no of moles of gas / total no of moles

molfraction times total prssure
product/raectants
temperature -if equilibrum moves to the right kp incraeses ( increase temp means lachetalia principle moves to the endothermic side vise versa
if equilibrim moves to the left kp reduces
pressure unaffect by pressure
catlysists sppeds up raection

39
Q

what is a half cell
what is electrochemical cells what are the compounds what happens
how to know what way a rection is going from emf vale
what dose a more negative and positive emf value tell us about what’s happened
what is a standard hydrogen electrode and why pt is used
what is the purpose of salt bridge give an example
what is equation for emf
how to formulate electrochemical cell
what are the standard conditions
what dose emf value tell us about feasibility of resections
define oxidising and reducing agents
steps in combining two half equations
how to write cell notation
where are electrochemical cells used
what happen in the positive and negative electrodes of lithium cell
what are fuel cells
what are the benefits and risks

A

metal in solution of its ions
2 help equations with salt bridge wires and voltmeter, redox reaction happens, electrons travel from more reactive to less reactive metal
salt bridge allow movement of ions eg -kno3
MOPRobelm negative emf is oxidise and positive emf is reduced OILRIG (FLIP half equation depending on if it reduced or oxidised)
standard electrode potentials =0.00v
its consists of 1 mol/dm-3 (might use h2so4 so half the moles) of h+ solution with pt electrode and h2 gas in 298k and 100kpa
metal/ion//ion/metal
positive emf value means its feasible
pt can be used as electrode if both metal and ions are solution its conductive and unreactive
non rechargeable cheaper
rechargeable reversal long term eg lithium ion battery which ahs electrode a -lithium cobalt oxide
electrode b graphite
electrolyte lithium salt
when recharging flip the reaction
fuel cells need continuous supply of chemicals
in a fuel cell h2 is pumped in and reacts with the oh- to create water and 4 e- and the electron move through anode platinum electrode to cathode platinum electrode where oxygen is pumped in where water reacts to make oh-and in the middle contains electrolytes for koh carries the oh- ions to anode
advantages -fuel cells efficient, more energy converted to kinetic energy waste product only water
disadvantages hydrogen highly farmable and expensive to transport

40
Q
  • Define Boston lowery acid and bases
  • why a logarithmic scale used to mesure hydrogen ion concentartion
  • how do you find ph and h+ concentration
A
  • Acid is a proton donor
    Bases are proton acceptors
    acid base reaction involves transfer of protons
  • Because the hydrogen ions in aqueous covers a very wide range
  • pH = –log10[H+]
    [H+]=10 to the power of (-pH)*
41
Q

what is kw equation
where does it come from
how dose temperature affect kw
how to use it to find ph of strong acid

A
  • kw=[H+][OH-]
  • The equation is the equilibrium conctant as water dssociates slightly
  • the forward reaction will be favoured, and more hydrogen ions and hydroxide ions will be formed. The effect of that is to increase the value of Kw as temperature increases.
  • kw will always equall (1times 10-14) and the [OH-] will be the same as the base concentartion so you can find [H+]
42
Q

what is the definition of a weak acid or base
what is the equation for Ka (weak acid)
how to find PKa from Ka and vise versa
what are the unites

A
  • They only dissociate slightly in aqueous solution
  • Ka=([H+][A−]/HA),or can be [H+]^2
  • (pKa = –log10 Ka) (10^-pka)
  • mol dm-3
43
Q
  • look through titration exam questions
  • explain how the graphs of combinations of a strong and weak acid and base would look like( look up)
  • what is an equivalance point
  • what are the different indicators used over different PH ranges and what are the color changes
A
  • equivalance point is when a tiny amount od base causes a sudden change in ph (where the acid is nutrilised)
  • phenolphthalein - colourless to pink (8.3 to 10)
  • methyl orange - red to yellow (3.1 to 4.4)
    • strong acid / strong base = both methyl orange and phenolphthaline
    • strong acid / weak base = only methyl orange
    • weak acid / strong base = only phenolphthaline
    • wak acid / wak base = neither dosent works
44
Q
  • what is the definition for buffer solutions
  • what is a acidic and basic buffer
  • what is a salt
  • where can buffers be used
  • explain what happen when there is a acid buffer and acid or bases is added from viodo
  • how to callculate ph of acidic buffer solution
A
  • buffer maintains a constant ph when small amounts of acids and bases are added or dillution
  • Acidic buffer solutions contain a weak acid and the salt of
    that weak acid
    Basic buffer solutions contain a weak base and the salt of
    that weak base.
  • salt is a chemical compound formed from an acid when an H+ ion from the acid has been replaced by a metal ion or another positive ion
  • shampoos and biological washing powders
  • find moles using volum and concentartion
    take smaller mole from laregr mole and use the smaleer mole for oh- rearrange equation and find h+ find PH
    (look up)
45
Q

What are trends in first ionisation energy and melting point of the elements Na–Ar the explain it in terms of terms of the structure of and bonding in the elements. explain the trends in atomic radius and first ionisation energy
explain the melting point of the elements in terms of their structure and bonding.

A
46
Q

The trends in atomic radius, first ionisation energy and melting point of the elements Mg–Ba

Students should be able to:

explain the trends in atomic radius and first ionisation energy
explain the melting point of the elements in terms of their structure and bonding.
The reactions of the elements Mg–Ba with water.

The use of magnesium in the extraction of titanium from TiCl4

The relative solubilities of the hydroxides of the elements Mg–Ba in water.

Mg(OH)2 is sparingly soluble.

The use of Mg(OH)2 in medicine and of Ca(OH)2 in agriculture.

The use of CaO or CaCO3 to remove SO2 from flue gases.

The relative solubilities of the sulfates of the elements Mg–Ba in water.

BaSO4 is insoluble.

The use of acidified BaCl2 solution to test for sulfate ions.

The use of BaSO4 in medicine.

Students should be able to:

explain why BaCl2 solution is used to test for sulfate ions and why it is acidified.

A
47
Q

properties are examined and explained. Fluorine is too dangerous to be used in a school laboratory

properties of elements in this group include explaining the trends in ability of the halogens to behave as oxidising agents and the halide ions to behave as reducing agents.

The trends in electronegativity and boiling point of the halogens.

Students should be able to:

explain the trend in electronegativity
explain the trend in the boiling point of the elements in terms of their structure and bonding.
The trend in oxidising ability of the halogens down the group, including displacement reactions of halide ions in aqueous solution.

The trend in reducing ability of the halide ions, including the reactions of solid sodium halides with concentrated sulfuric acid.

The use of acidified silver nitrate solution to identify and distinguish between halide ions.

The trend in solubility of the silver halides in ammonia.

Students should be able to explain why:

silver nitrate solution is used to identify halide ions
the silver nitrate solution is acidified
ammonia solution is added.

A
48
Q

How reaction of chlorine with water to form chloride ions and chlorate(I) ions.

How reaction of chlorine with water to form chloride ions and oxygen.
What are some society assesses the advantages and disadvantages when deciding if chemicals should be added to water supplies.

The use of chlorine in water treatment.

Appreciate that the benefits to health of water treatment by chlorine outweigh its toxic effects.

The reaction of chlorine with cold, dilute, aqueous NaOH and uses of the solution formed.

Required practical 4Carry out simple test-tube reactions to identify:
cations – Group 2, NH4+
anions – Group 7 (halide ions), OH–, CO32–, SO42

A
49
Q

The reactions of Na and Mg with water.

The trends in the reactions of the elements Na, Mg, Al, Si, P and S with oxygen, limited to the formation of Na2O, MgO, Al2O3, SiO2, P4O10, SO2 and SO3

The trend in the melting point of the highest oxides of the elements Na–S

The reactions of the oxides of the elements Na–S with water, limited to Na2O, MgO, Al2O3, SiO2, P4O10, SO2 and SO3, and the pH of the solutions formed.

The structures of the acids and the anions formed when P4O10, SO2 and SO3 react with water.

Students should be able to:

explain the trend in the melting point of the oxides of the elements Na–S in terms of their structure and bonding
explain the trends in the reactions of the oxides with water in terms of the type of bonding present in each oxide
write equations for the reactions that occur between the oxides of the elements Na–S and given acids and bases.

A
50
Q

what is a monodentate, bidentate, and multidentate ligand give examples
what are the 2 reasons why complex ligands can be replaced
why might replacing h20 ligand with Cl- change co ordinate number
why might a substitution reaction be incomplete
what is haem
how hemoglobin transports oxygen
why is carbon monoxide toxic
explain chetate effect
what is the shape and angle of the complex if it has 6 coordinate bonds
what is the shape and angle of the complex if it has 4 coordinate bonds
what is needed to form an optical isomer for complex ions
how can octahedral and square planer displaced as cis trans
what is cisplatin’s structure
what is the linear complex formed with Ag

A

when one co ordinate bonds, eg H2O nh3 or Cl-
when two co ordinated bonds eg ethane-1,2-diamine or ethanedioate
when more than one co ordinate bonds eg EDTA^4-
the ligands can form stronger coordinate bond or there’s high concentration of ligand
as cl- is larger than h2o only 4 ligands can be formed
because theses not enough of ligands eg NH3 to replace the water ligands
it is a multidentate ligand found in the molecule hemoglobin and forms 4 (nitrogen) out of the 6 ligands attached to fe2+, another two comes from globin and oxygen or water molecule
oxygen is replaced by water when it reaches the muscle
it attaches to the fe2+ and prevents oxygen from attaching as a ligand so oxygen is not transported
The substitution of monodentate ligand with a bidentate or a multidentate ligand leads to a more stable complex. eg if 2 reactant molecules turn into 7 product molecules the entropy increases and reaction favor higher entropy
octahedral with 90 degrees
tetrahedral 109.5 degrees
3 bidentate ligands
if the ligand of the same type is on opposite side then its trans if its on the same side then its cis for both octahedral and square planer
they have 2 nh3 on top and 2 cl- on the bottom its a cis isomer
it has ag with nh3 on both sides

51
Q

Name the different ions , oxidation states and colours of vanadium ions
How to reduce vanadium
Google the equation of each reductions of vanadium ions
What are redox potentials
What dose the redox potential tell us about the half equation
In What environment is standard electrode potentials measured and what happen to the metal ion in this environment
2 reasons why redox potential might be higher or lower than the standard value
What is a tollens reagent
what is a redox titration fe2+,c2o4 2-,mno4-
how do you balance a half equation

A

Zinc in acid solution (H+)
Redox potential is the how easily an ion can be reduced same as electrode potentials
More postive redox potential means it’s least stable and most likely to be reduced and that it’s more likely to be feasible
It’s measured in aqueous solution so it will be surrounded by water ligand’s
If stronger ligands such as NH3 attaches to the metal ion it may affect redox potential Or if the solution is more acidic means it would have larger electrode potentials therefore it would be easier to reduce
It is a transition metal(silver) which forms a complex that helps distinguish between aldehydes and Ketons
Cr2O7- (aq) + 14H+ (aq) + 6e- → 2Cr3+ (aq) + 7H2O (l)
MnO4- (aq) + 8H+ (aq) + 5e- → Mn2+ (aq) + 4H2O (aq)
Fe2+ → Fe3+ +e-
balance the moles
balance oxygen by adding h20 to the other side balance the no of hydrogen on to the first side balance electron
combining two equations-times equation by no of electrons

52
Q

what do ligands do to the d orbit
explain how different colors are seen in terms of electrons and wavelengths
what determines the color
what does energy gap depend on
what is the equation to find energy gap
what is a spectroscopy used for and what can be used to find the absorbance

A

when ligands are formed the d orbital which has 5 sub shells splits, where one orbital will have a higher energy than the other
when different wavelengths of light hit electron some are absorbed this cause electron to move up to the higher energy subshell and back, the wavelength of light not absorbed is reflected
the energy energy gap of the split 3d sub shell determines the color
the type of metal ions, oxidation state, type of ligands and the number of co ordinated bonds
energy gap =plank constant (h) times frequency of light (hz)
it can be used to find concentration of meatal ions, the more concentrated it is the more colored it is and the more light it absorbs which is recorded by the calorimeter

53
Q

why are transition metal good catalysis’s
what happen during a contact process
what is a heterogeneous catalyst
how can the rate of reaction be increased in heterogenous catalysts, what can they use to do this
what are example of heterogenous catalyst and where there used
what is catalyst poising, why might affect industries
what are homogenous catalysts, give example
what is an autocatalysis
show the equation to how is mn3+formed from mn2+ to be the autocatalysis for c204^2-

A

the vacant d orbital means that that the oxidations states can change
modern industrial method of producing sulfuric acid, during it v205 (vanadium) can go form 5+ to 4+ to oxidise so2 to so3 and vanadium goes back to 5+ oxidation by oxygen
they are in a different phase from the reactants eg catalysts may be solid and the reacts are gases
they would have to increase the rate of reaction this can be don by using a support medium they minimise the cost as only a small amount of medium is used to cover catalysts
Fe in harbor cycle for making ammonia
vanadium v204 in contact process making sulfuric acid
Heterogeneous catalysts can become poisoned by impurities that block the active sites and consequently have reduced efficiency; this has a cost implication
they are in the same phase as the reactants, the reaction go through an intermediate spices for example fe2+ haps catalyse s2o8^2- an I- as both are negative they repel so less likely to collide but fe2= is turned into fe 3+ byes s2o8^-2 and the the fe 3+ oxidise I- to make I
homogeneous catalysts has the same physical state as the reactants, they combine with the reactants to form a intermediate spices with reacts again to create the products and the original catalyst
its is the when the catalyst has to be made through a reaction and then this product acts as the catalyst
4Mn2+ (aq) + MnO4– (aq) + 8H+ (aq) → 5Mn3+ (aq) + 4H2O (aq)

2Mn3+ (aq) + C2O42- (aq) → 2CO2 (g) + 2Mn2+ (aq)

54
Q

what happens when transition metals dissolve in aquas solution
why 3+metal aqua ions will form a more acidic solution than 2+
what happen when Oh- is added to metal aqua solution
what is an amphoteric in terms of metal hydroxides give example
show how the colour and the products formed when (cu2+,fe2+,al3+,fe3+) metal aqua ions react with oh-/nh3, excess oh-,excess nh3and na2co3

A

they become metal q=aqua ion complexes with six water ligands attached thro coordinate bons between electrons on the oxygen
as 3+ ions have greater charge it is mor strongly bonded to the electron son the oxygen however this mean that the o-h bond on water is weaker so it more likely to split as a result more h+ ions are formed and is more acidic
the oh reacts with the h30 causing the equlibrium to move to the left as a result the h2o ligands are replaced by 0h- according to the charge of the ion
they can react with acid and base eg al hydroxides
Al(OH)3(H2O)3 (s) + 3HCl (aq) → [Al(H2O)6] 3+ (aq) + 3Cl- (aq)
Al(OH)3(H2O)3 (s) + 3HCl (aq) → [Al(H2O)6] 3+ (aq) + 3Cl- (aq)

fe2+
[Fe(H2O)6] 2+ (aq) + 2OH– (aq) → Fe(H2O)4(OH)2 (s) + 2H2O (l) (green ppt)
[Fe(H2O)6] 2+ (aq) + 2NH3 (aq) → Fe(H2O)4(OH)2 (s) + 2NH4+ (aq) (stays green solution -no change)
[Fe(H2O)6] 2+ (aq) + CO32- (aq) → FeCO3 (s) + 6H2O (l) (green ppt)
cu2+
[Cu(H2O)6] 2+ (aq) + 2OH– (aq) → Cu(H2O)4(OH)2 (s) +2 H2O (l) (blue ppt)
[Cu(H2O)6] 2+ (aq) + 2NH3 (aq) → Cu(H2O)4(OH)2 (s) + 2NH4+ (aq) (not in exess same as oh- blur ppt)
Cu(H2O)4(OH)2 (s) + 4NH3 (aq) → [Cu(NH3)4(H2O)2 ]2+ (aq) + + 2OH- (aq) + 2H2O (l)(in exess- deep blur solution)
[Cu(H2O)6] 2+ (aq) + CO32- (aq) → CuCO3 (s) + 6H2O (l) (green blue ppt)
al3+
[Al(H2O)6] 3+ (aq) +3 OH– (aq) → Al(H2O)3(OH)3 (s) + 3H2O (l) (white ppt)
[Al(H2O)6] 3+ (aq) + 3NH3 (aq) → Al(H2O)3(OH)3 (s) + 3NH4+ (aq) (same as oh- white ppt)
2[Al(H2O)6]3+ + 3CO32− (aq) → 2Al(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l)(white ppt)
fe3+
[Fe(H2O)6] 3+ (aq) + 3OH– (aq) → Fe(H2O)3(OH)3 (s) + 3H2O (l) (brown ppt)
[Fe(H2O)6] 3+ (aq) + 3NH3 (aq) → Fe(H2O)3(OH)3 (s) + 3NH4+ (aq)(same as oh- brown ppt)
2[Fe(H2O)6]3+ (aq) + 3CO32− (aq) → 2Fe(H2O)3(OH)3 (s) + 3CO2 (g) + 3H2O (l) (brown ppt)

55
Q

Organic compounds can be represented by:

empirical formula
molecular formula
general formula
structural formula
displayed formula
skeletal formula.
The characteristics of a homologous series, a series of compounds containing the same functional group.

IUPAC rules for nomenclature.

Students should be able to:

draw structural, displayed and skeletal formulas for given organic compounds
apply IUPAC rules for nomenclature to name organic compounds limited to chains and rings with up to six carbon atoms each
apply IUPAC rules for nomenclature to draw the structure of an organic compound from the IUPAC name limited to chains and rings with up to six carbon atoms each.

A
56
Q

Opportunities for skills development
Reactions of organic compounds can be explained using mechanisms.

Free-radical mechanisms:

the unpaired electron in a radical is represented by a dot
the use of curly arrows is not required for radical mechanisms.
Students should be able to:

write balanced equations for the steps in a free-radical mechanism.
Other mechanisms:

the formation of a covalent bond is shown by a curly arrow that starts from a lone electron pair or from another covalent bond
the breaking of a covalent bond is shown by a curly arrow starting from the bond.
Students should be able to:

outline mechanisms by drawing the structures of the species involved and curly arrows to represent the movement of electron pairs

A
57
Q

Structural isomerism.

Stereoisomerism.

E–Z isomerism is a form of stereoisomerism and occurs as a result of restricted rotation about the planar carbon–carbon double bond.

Cahn–Ingold–Prelog (CIP) priority rules.

Students should be able to:

define the term structural isomer
draw the structures of chain, position and functional group isomers
define the term stereoisomer
draw the structural formulas of E and Z isomers
apply the CIP priority rules to E and Z isomers.

A
58
Q

Alkanes are saturated hydrocarbons.

Petroleum is a mixture consisting mainly of alkane hydrocarbons that can be separated by fractional distillation.

A
59
Q

Cracking involves breaking C–C bonds in alkanes.

Thermal cracking takes place at high pressure and high temperature and produces a high percentage of alkenes (mechanism not required).

Catalytic cracking takes place at a slight pressure, high temperature and in the presence of a zeolite catalyst and is used mainly to produce motor fuels and aromatic hydrocarbons (mechanism not required).

Students should be able to:

explain the economic reasons for cracking alkanes.

A
60
Q

Alkanes are used as fuels.

Combustion of alkanes and other organic compounds can be complete or incomplete.

The internal combustion engine produces a number of pollutants including NOx, CO, carbon and unburned hydrocarbons.

These gaseous pollutants from internal combustion engines can be removed using catalytic converters.

Combustion of hydrocarbons containing sulfur leads to sulfur dioxide that causes air pollution.

Students should be able to:

explain why sulfur dioxide can be removed from flue gases using calcium oxide or calcium carbonate.

A
61
Q

The reaction of methane with chlorine.

Students should be able to:

explain this reaction as a free-radical substitution mechanism involving initiation, propagation and termination steps.

A
62
Q

Halogenoalkanes contain polar bonds.

Halogenoalkanes undergo substitution reactions with the nucleophiles OH–, CN– and NH3

Students should be able to:

outline the nucleophilic substitution mechanisms of these reactions
explain why the carbon–halogen bond enthalpy influences the rate of reaction.

A
63
Q

The concurrent substitution and elimination reactions of a halogenoalkane (eg 2-bromopropane with potassium hydroxide).

Students should be able to:

explain the role of the reagent as both nucleophile and base
outline the mechanisms of these reactions.

A
64
Q

Ozone, formed naturally in the upper atmosphere, is beneficial because it absorbs ultraviolet radiation.

Chlorine atoms are formed in the upper atmosphere when ultraviolet radiation causes C–Cl bonds in chlorofluorocarbons (CFCs) to break.

Chlorine atoms catalyse the decomposition of ozone and contribute to the hole in the ozone layer.

Appreciate that results of research by different groups in the scientific community provided evidence for legislation to ban the use of CFCs as solvents and refrigerants. Chemists have now developed alternative chlorine-free compounds.

Students should be able to:

use equations, such as the following, to explain how chlorine atoms catalyse decomposition of ozone:
Cl• + O3 → ClO• + O2 and ClO• + O3 → 2O2 + Cl•

A
65
Q

Alkenes are unsaturated hydrocarbons.

Bonding in alkenes involves a double covalent bond, a centre of high electron density.

A
66
Q

Electrophilic addition reactions of alkenes with HBr, H2SO4 and Br2

The use of bromine to test for unsaturation.

The formation of major and minor products in addition reactions of unsymmetrical alkenes.

Students should be able to:

outline the mechanisms for these reactions
explain the formation of major and minor products by reference to the relative stabilities of primary, secondary and tertiary carbocation intermediates.

A
67
Q

Addition polymers are formed from alkenes and substituted alkenes.

The repeating unit of addition polymers.

IUPAC rules for naming addition polymers.

Addition polymers are unreactive.

Appreciate that knowledge and understanding of the production and properties of polymers has developed over time.

Typical uses of poly(chloroethene), commonly known as PVC, and how its properties can be modified using a plasticiser.

Students should be able to:

draw the repeating unit from a monomer structure
draw the repeating unit from a section of the polymer chain
draw the structure of the monomer from a section of the polymer
explain why addition polymers are unreactive
explain the nature of intermolecular forces between molecules of polyalkenes.

A
68
Q

Alcohols are produced industrially by hydration of alkenes in the presence of an acid catalyst.

Ethanol is produced industrially by fermentation of glucose. The conditions for this process.

Ethanol produced industrially by fermentation is separated by fractional distillation and can then be used as a biofuel.

Students should be able to:

explain the meaning of the term biofuel
justify the conditions used in the production of ethanol by fermentation of glucose
write equations to support the statement that ethanol produced by fermentation is a carbon neutral fuel and give reasons why this statement is not valid
outline the mechanism for the formation of an alcohol by the reaction of an alkene with steam in the presence of an acid catalyst
discuss the environmental (including ethical) issues linked to decision making about biofuel use.

A
69
Q

Alcohols are classified as primary, secondary and tertiary.

Primary alcohols can be oxidised to aldehydes which can be further oxidised to carboxylic acids.

Secondary alcohols can be oxidised to ketones.

Tertiary alcohols are not easily oxidised.

Acidified potassium dichromate(VI) is a suitable oxidising agent.

Students should be able to:

write equations for these oxidation reactions (equations showing [O] as oxidant are acceptable)
explain how the method used to oxidise a primary alcohol determines whether an aldehyde or carboxylic acid is obtained
use chemical tests to distinguish between aldehydes and ketones including Fehling’s solution and Tollens’ reagent.

A
70
Q

Alkenes can be formed from alcohols by acid-catalysed elimination reactions.

Alkenes produced by this method can be used to produce addition polymers without using monomers derived from crude oil.

Students should be able to:
outline the mechanism for the elimination of water from alcohols.
AT b, d, g and k

PS 4.1
Students could carry out the preparation of cyclohexene from cyclohexanol, including purification using a separating funnel and by distillation.
Required practical 5

Distillation of a product from a reaction.

A
71
Q

The reactions of functional groups listed in the specification.

Students should be able to:

identify the functional groups using reactions in the specification.
AT b, d and k

PS 2.2, 2.3 and 4.1
Students could carry out test-tube reactions in the specification to distinguish alcohols, aldehydes, alkenes and carboxylic acids.
Required practical 6

Tests for alcohol, aldehyde, alkene and carboxylic acid.

A
72
Q

Mass spectrometry can be used to determine the molecular formula of a compound.

Students should be able to:

use precise atomic masses and the precise molecular mass to determine the molecular formula of a compound.

A
73
Q

Bonds in a molecule absorb infrared radiation at characteristic wavenumbers.

‘Fingerprinting’ allows identification of a molecule by comparison of spectra.

Students should be able to:

use infrared spectra and the Chemistry Data Sheet or Booklet to identify particular bonds, and therefore functional groups, and also to identify impurities.
The link between absorption of infrared radiation by bonds in CO2, methane and water vapour and global warming.

A
74
Q

Optical isomerism is a form of stereoisomerism and occurs as a result of chirality in molecules, limited to molecules with a single chiral centre.

An asymmetric carbon atom is chiral and gives rise to optical isomers (enantiomers), which exist as non super-imposable mirror images and differ in their effect on plane polarised light.

A mixture of equal amounts of enantiomers is called a racemic mixture (racemate).

Students should be able to:

draw the structural formulas and displayed formulas of enantiomers
understand how racemic mixtures (racemates) are formed and why they are optically inactive.

A
75
Q

Aldehydes are readily oxidised to carboxylic acids.

Chemical tests to distinguish between aldehydes and ketones including Fehling’s solution and Tollens’ reagent.

Aldehydes can be reduced to primary alcohols, and ketones to secondary alcohols, using NaBH4 in aqueous solution. These reduction reactions are examples of nucleophilic addition.

The nucleophilic addition reactions of carbonyl compounds with KCN, followed by dilute acid, to produce hydroxynitriles.

Aldehydes and unsymmetrical ketones form mixtures of enantiomers when they react with KCN followed by dilute acid.

The hazards of using KCN.

Students should be able to:

write overall equations for reduction reactions using [H] as the reductant
outline the nucleophilic addition mechanism for reduction reactions with NaBH4 (the nucleophile should be shown as H–)
write overall equations for the formation of hydroxynitriles using HCN
outline the nucleophilic addition mechanism for the reaction with KCN followed by dilute acid
explain why nucleophilic addition reactions of KCN, followed by dilute acid, can produce a mixture of enantiomers.

A
76
Q

The structures of:

carboxylic acids
esters.
Carboxylic acids are weak acids but will liberate CO2 from carbonates.

Carboxylic acids and alcohols react, in the presence of an acid catalyst, to give esters.

Common uses of esters (eg in solvents, plasticisers, perfumes and food flavourings).

Vegetable oils and animal fats are esters of propane-1,2,3-triol (glycerol).

Esters can be hydrolysed in acid or alkaline conditions to form alcohols and carboxylic acids or salts of carboxylic acids.

Vegetable oils and animal fats can be hydrolysed in alkaline conditions to give soap (salts of long-chain carboxylic acids) and glycerol.

Biodiesel is a mixture of methyl esters of long-chain carboxylic acids.

Biodiesel is produced by reacting vegetable oils with methanol in the presence of a catalyst.

A
77
Q

The structures of:

acid anhydrides
acyl chlorides
amides.
The nucleophilic addition–elimination reactions of water, alcohols, ammonia and primary amines with acyl chlorides and acid anhydrides.

The industrial advantages of ethanoic anhydride over ethanoyl chloride in the manufacture of the drug aspirin.

Students should be able to outline the mechanism of nucleophilic addition–elimination reactions of acyl chlorides with water, alcohols, ammonia and primary amines.
Required practical 10

Preparation of:
a pure organic solid and test of its purity
a pure organic liquid.

A
78
Q

The nature of the bonding in a benzene ring, limited to planar structure and bond length intermediate between single and double.

Delocalisation of p electrons makes benzene more stable than the theoretical molecule cyclohexa-1,3,5-triene.

Students should be able to:

use thermochemical evidence from enthalpies of hydrogenation to account for this extra stability
explain why substitution reactions occur in preference to addition reactions.

A
79
Q

Electrophilic attack on benzene rings results in substitution, limited to monosubstitutions.

Nitration is an important step in synthesis, including the manufacture of explosives and formation of amines.

Friedel–Crafts acylation reactions are also important steps in synthesis.

Students should be able to outline the electrophilic substitution mechanisms of:

nitration, including the generation of the nitronium ion
acylation using AlCl3 as a catalyst.

A
80
Q

Primary aliphatic amines can be prepared by the reaction of ammonia with halogenoalkanes and by the reduction of nitriles.

Aromatic amines, prepared by the reduction of nitro compounds, are used in the manufacture of dyes.

A
81
Q

Amines are weak bases.

The difference in base strength between ammonia, primary aliphatic and primary aromatic amines.

Students should be able to:

explain the difference in base strength in terms of the availability of the lone pair of electrons on the N atom.

A
82
Q

Amines are nucleophiles.

The nucleophilic substitution reactions of ammonia and amines with halogenoalkanes to form primary, secondary, tertiary amines and quaternary ammonium salts.

The use of quaternary ammonium salts as cationic surfactants.

The nucleophilic addition–elimination reactions of ammonia and primary amines with acyl chlorides and acid anhydrides.

Students should be able to outline the mechanisms of:

these nucleophilic substitution reactions
the nucleophilic addition–elimination reactions of ammonia and primary amines with acyl chlorides.

A
83
Q

Condensation polymers are formed by reactions between:

dicarboxylic acids and diols
dicarboxylic acids and diamines
amino acids.
The repeating units in polyesters (eg Terylene) and polyamides (eg nylon 6,6 and Kevlar) and the linkages between these repeating units.

Typical uses of these polymers.

Students should be able to:

draw the repeating unit from monomer structure(s)
draw the repeating unit from a section of the polymer chain
draw the structure(s) of the monomer(s) from a section of the polymer
explain the nature of the intermolecular forces between molecules of condensation polymers.

A
84
Q

Polyalkenes are chemically inert and non-biodegradable.

Polyesters and polyamides can be broken down by hydrolysis and are biodegradable.

The advantages and disadvantages of different methods of disposal of polymers, including recycling.

Students should be able to:

explain why polyesters and polyamides can be hydrolysed but polyalkenes cannot.

A
85
Q

Amino acids have both acidic and basic properties, including the formation of zwitterions.

Students should be able to draw the structures of amino acids as zwitterions and the ions formed from amino acids:

in acid solution
in alkaline solution.

A
86
Q

Proteins are sequences of amino acids joined by peptide links.

The importance of hydrogen bonding and sulfur–sulfur bonds in proteins.

The primary, secondary (α-helix and β–pleated sheets) and tertiary structure of proteins.

Hydrolysis of the peptide link produces the constituent amino acids.

Amino acids can be separated and identified by thin-layer chromatography.

Amino acids can be located on a chromatogram using developing agents such as ninhydrin or ultraviolet light and identified by their Rf values.

Students should be able to:

draw the structure of a peptide formed from up to three amino acids
draw the structure of the amino acids formed by hydrolysis of a peptide
identify primary, secondary and tertiary structures in diagrams
explain how these structures are maintained by hydrogen bonding and S–S bonds
calculate Rf values from a chromatogram

A
87
Q

Enzymes are proteins.

The action of enzymes as catalysts, including the concept of a stereospecific active site that binds to a substrate molecule.

The principle of a drug acting as an enzyme inhibitor by blocking the active site.

Computers can be used to help design such drugs.

Students should be able to:

explain why a stereospecific active site can only bond to one enantiomeric form of a substrate or drug.

A
88
Q

The structures of the phosphate ion, 2-deoxyribose (a pentose sugar) and the four bases adenine, cytosine, guanine and thymine are given in the Chemistry Data Booklet.

A nucleotide is made up from a phosphate ion bonded to 2-deoxyribose which is in turn bonded to one of the four bases adenine, cytosine, guanine and thymine.

A single strand of DNA (deoxyribonucleic acid) is a polymer of nucleotides linked by covalent bonds between the phosphate group of one nucleotide and the 2-deoxyribose of another nucleotide. This results in a sugar-phosphate-sugar-phosphate polymer chain with bases attached to the sugars in the chain.

DNA exists as two complementary strands arranged in the form of a double helix.

Students should be able to:

explain how hydrogen bonding between base pairs leads to the two complementary strands of DNA.

A
89
Q

The Pt(II) complex cisplatin is used as an anticancer drug.

Cisplatin prevents DNA replication in cancer cells by a ligand replacement reaction with DNA in which a bond is formed between platinum and a nitrogen atom on guanine.

Appreciate that society needs to assess the balance between the benefits and the adverse effects of drugs, such as the anticancer drug cisplatin.

Students should be able to:

explain why cisplatin prevents DNA replication
explain why such drugs can have adverse effects.

A
90
Q

The synthesis of an organic compound can involve several steps.

Students should be able to:

explain why chemists aim to design processes that do not require a solvent and that use non-hazardous starting materials
explain why chemists aim to design production methods with fewer steps that have a high percentage atom economy
use reactions in this specification to devise a synthesis, with up to four steps, for an organic compound.

A
91
Q

Appreciation that scientists have developed a range of analytical techniques which together enable the structures of new compounds to be confirmed.

Nuclear magnetic resonance (NMR) gives information about the position of 13C or 1H atoms in a molecule.

13C NMR gives simpler spectra than 1H NMR.

The use of the δ scale for recording chemical shift.

Chemical shift depends on the molecular environment.

Integrated spectra indicate the relative numbers of 1H atoms in different environments.

1H NMR spectra are obtained using samples dissolved in deuterated solvents or CCl4

The use of tetramethylsilane (TMS) as a standard.

Students should be able to:

explain why TMS is a suitable substance to use as a standard
use 1H NMR and 13C NMR spectra and chemical shift data from the Chemistry Data Booklet to suggest possible structures or part structures for molecules
use integration data from 1H NMR spectra to determine the relative numbers of equivalent protons in the molecule
use the n+1 rule to deduce the spin–spin splitting patterns of adjacent, non-equivalent protons, limited to doublet, triplet and quartet formation in aliphatic compounds.

A
92
Q

Chromatography can be used to separate and identify the components in a mixture.

Types of chromatography include:

thin-layer chromatography (TLC) – a plate is coated with a solid and a solvent moves up the plate
column chromatography (CC) – a column is packed with a solid and a solvent moves down the column
gas chromatography (GC) – a column is packed with a solid or with a solid coated by a liquid, and a gas is passed through the column under pressure at high temperature.
Separation depends on the balance between solubility in the moving phase and retention by the stationary phase.

Retention times and Rf values are used to identify different substances.

The use of mass spectrometry to analyse the components separated by GC.

Students should be able to:

calculate Rf values from a chromatogram
compare retention times and Rf values with standards to identify different substances

A
93
Q

what happen when mg and na reacts with water which is more reactive
what elements to know about in this section how they react with air
what happens when period 3 elements react with oxygen
what meting point of period 3 metal oxides
why dose na2o produce solution with huger ph than MgO a sthe hydroxide produced by na 2o is more soluble in water tha mgO

A

na+ and mg2+ is formed, na is more reactive as i is easier to reove an electron from na than mg (manisum /sodium hydroxideoxide and h2is formed) with staem it forms metal oxide instaed of hydroxides
na mg(reacts vigarously) al si(reacts slowly) p(spontanious combustion) s (burns)
they from oxides eg na 20,mgo,sio2,p4o10
na2o and al2o3 adn mg2o has gain ionic structure so hig mp
mgo higer as it has 2+ so hardeer to remove electron
alo3 low electronegtivity between al and o so easler to get electron
si has covalent bonds
p4o10 so2 simple molecular structure

chemsitry (2 decks)

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