Definitions Flashcards

Question

Why solutions can be stable for long time despite E° value of reaction being spontaneous?

Answer 1

Actual reaction conditions could vary greatly from the standard conditions. (Temp, pressure, concentration)

Answer 2

Increases rate of reaction by providing an alternative pathway with lower activation energy for reaction to occur, and is chemically unchanged (and regenerated) by the end of the reaction. Enzymes just add ‘biological’ and ‘protein in nature’

Answer 3

Highly selective Only work over a narrow pH range and temperature range (easily denatured) Specific in nature (can only be used for 1 task) highly efficient Neither homogenous nor heterogeneous, **colloidal in nature**

Answer 4

Catalyst is in the same physical state as the reactants

Answer 5

Catalyst is in a different physical state from the reactants

Answer 6

Reactants and products are in the same physical state

Answer 7

Reactants and products are in different physical states

Answer 8

Conc of solids, conc of more liquids in heterogenous, conc of solvents

Answer 9

Heterogenous: Reactants form weak interactions with surface of TM, covalent bonds in reactant molecules weakened. Ea falls, and surface conc of reactant molecules increases (allows more to come into close contact with each other in correct orientation) —> rate of reaction increases —> products desorp and catalyst can be used for other reactants Homogenous: variable oxidation states allow TM to oxidise/reduce compounds and be regenerated by transitioning btw oxidation states —> lower activation energy needed for reaction to occur (especially btw like charge ions with very high repulsion btw them)

Answer 10

Central metal atom or ions surrounded by ligands that are bonded to it through a dative bond

Answer 11

Ligands are neutral molecules or anions that have at least 1 lone pair of electrons that can be used to form a dative bond with a transition metal atom or ion.

Answer 12

Number of dative bonds formed between ligands and transition metal atom or ion in a complex

Answer 13

TM high charge density, highly polarising, attract LP of electrons from surrounding particles towards itself. Can accommodate more electrons also because energetically accessible vacant 3d, 4s, 4p, 4d electron subshells. Overall of empty orbital in TM atom or ion and fully filled orbital of ligand —> forms a dative bond

Answer 14

2024 prelim p2 qn - haemoglobin + 4O2 ⇌ oxyhaemoglobin + 4H2O - at high conc of O2 (eg lungs), ligand exchange happens, water ligands replaced with O2 ligands, POE shift right, H2O and oxyhaemoglobin released

Answer 15

Cu: Cu(H2O)6 2+ blue Cu(NH3)4(H2O)2 2+ dark blue CuCl4 2- yellow CuI white ppt Cu2O brick red ppt Cu(OH)2 blue ppt Cr: Cr2O7 2- orange CrO4 2- yellow Cr(H2O)6 3+ green Cr(OH)3 grey green ppt **Cr(OH)6 3- dark green** Fe: Fe(H2O)6 2+ pale green Fe(H2O)6 3+ yellow Fe(H2O)5SCN 2+ blood red Fe(OH)2 green ppt Fe(OH)3 reddish-brown ppt Mn: MnO4 - purple Mn(H2O)6 2+ colourless/pale pink Mn(OH)2 off-white ppt Mn(OH)3 **brown** MnO2 brown ppt Al: Al(OH)3 white Al(OH)4 - colourless Ag: Ag(NH3)2 + colourless AgCl white ppt AgBr off-white ppt AgI yellow ppt Zn: Zn(OH)2 white Zn(OH)4 2- colourless Zn(H2O)6 2+ colourless Zn(NH3)4 2+ colourless

Answer 16

**Assuming shape of complex as octahedral,** due to ligand approach, orbitals are split into 2 dif energy levels (d-d splitting) An electron from the lower energy level absorbs a photon from the electromagnetic spectrum and is promoted to a higher energy level. Wavelength of photon is determined by degree of splitting. The colour observed is complement to those absorbed in visible region of spectrum.

Answer 17

eFOA btw oppositely charged ions

Answer 18

eFOA between sea of delocalised electrons and lattice of positively charged ions

Answer 19

eFOA between shared pair of electrons and positively charged surrounding nuclei

Answer 20

Ionic bond strength: lattice energy (energy released when 1 mole of ionic solid is formed from its isolated gaseous ions an infinite distance apart)

Answer 21

Charge density of cation No of delocalised electrons —> more extensive/stronger eFOA

Answer 22

Multiplicity of bond: more shared electron pairs = stronger eFOA between shared pair of electrons and nuclei of atoms = stronger covalent bond **Size of atom**: smaller = less diffuse orbitals = more effective overlap = stronger covalent bond Proximity of lone pairs: closer together = more (excessive) repulsion between LP = weaker covalent bond Polarity: comparable size, induction of partial charges due to electronegativity differences = more polar bond, eFOA between partial charges strengthens covalent bond

Answer 23

One compound has a lone pair of electrons available for donation and the other has **energetically accessible** orbitals that it can use to accept electrons NOT THE SAME as H bond! Don’t mix up! Neither need to be highly electronegative for this

Answer 24

Head on overlap, electron density concentrated between the nuclei of the 2 bonding atoms

Answer 25

Side on overlap, less effective, region of overlap is above and below nuclear axis, node present

Answer 26

Region of space in which there is a zero probability of locating electrons

Answer 27

Ionic bonding, assumed to be perfectly symmetrical spheres. But when oppositely charged ions are close to each other, partial sharing of electrons because cation attracts valence electrons of anion towards itself and polarises electron cloud of anion. Partial covalent character

Answer 28

Charge density of cation Polarisibility of anion

Answer 29

Perfect covalent bond—> non polar only exists when electronegativities are exactly the same Most molecules, not. Partial positive and partial negative charges induced, ionic character

Answer 30

Net dipole moment (dipole moment = charge x distance between the nuclei of the 2 atoms)

Answer 31

eFOA between polar ends of the molecule / between opposite partial charges

Answer 32

eFOA between highly electron deficient H (that is covalently bonded to a highly electronegative atoms) and lone pair of electrons on highly electronegative atom

Answer 33

Always satisfy Side atoms first then consider whether centre one has energetically accessible centre

Answer 34

All covalent, because high charge density of cations causes electron cloud of anion to be polarised to a very large extent (GMS) But for AlCl3 if they ask structure, it is actually GICLS as a solid, SMS as molten/gas (period 3 notes) so this one specifically needa see context

Answer 35

Much more effective overlaps than s-s or p-p so much stronger bond (s orbitals spend more time close to their respective nuclei, and less in the binding region. p orbitals spend more time in the binding region; that is close both the nuclei; thus s-p overlap forming a stronger bond than s-s overlap - https://www.physicsforums.com/threads/why-s-p-orbital-overlap-is-stronger-than-s-s-overlap.498941/#)

Answer 36

Explain the covalent character thing LE calculated on assumption that ions are 2 perfectly spherical point charges but there’s a disagreement in values for experimental (consider polarising power of cation and polarisability of anion —> degree of electron cloud distortion, electron sharing and covalent character). Higher covalent character = larger disagreement. **FYI** Hey apparently they use coloumb’s law to calculate; link btw phys electric fields and like chem ionic charge Larger theoretical than experiential suggests covalent bonds —> ionic weakened (When ionic bonds exhibit covalent character, there is a degree of sharing of electron density between the ions. This sharing reduces the effective charge that each ion experiences, as the electron cloud is distorted so strength of ionic bonds reduced.) vs larger experimental than theoretical suggests more energy is needed to overcome the covalent bonds between the lattice ions to break up the lattice. (Since additional bonds and interactions created ig)

Answer 37

Giant metallic crystal lattice structure: orderly arrangement of metal cations and sea of delocalised electrons held together by strong eFOA between … Giant molecular structure: each c atom is covalent bonded to .. other atoms with eFOA between shared pair of electron and nuclei of surrounding atoms … (hexagonal + layers w id-id due to delocalisation of remaining electron / extensive tetrahedral network) Simple molecular structure: weak interactions (pd-pd/id-id/h bond) between … molecules Giant ionic crystal lattice structure: regular arrangement of cations and anions held together by strong eFOA between opp charged ions

Answer 38

Ions/electrons can act as mobile charge carriers to carry charges around —> can conduct electricity Non-conductor: no mobile charge carrier since covalent molecules in SMS are neutral/since ions are held in fixed position by strong ionic bonds (GIS) GMS- graphite structure, good conductors in direction parallel to layers as delocalised electrons act as mobile charge carrier under applied PD but poor conductor in direction perpendicular to plane as delocalised electrons cannot jump across layers

Answer 39

GMCLS: ductile and malleable (mobility of delocalised electrons allows layers of cations to slide over each other without shattering structure) GICLS: brittle (slight displacement brings together ions of like charge, shattering lattice structure), hard (strong eFOA) GMS: diamond: hard (strong eFOA), graphite: flaky and slippery (weak idid between layers) SMS: soft (weak idid)

Answer 40

Structure Bonding Energy

Answer 41

Lone pair held closer to nucleus than bond pair since bp shared w another atom

Answer 42

Electron pairs arrange themselves ard central atom to reduce repulsion, because LP-LP repulsion>LP-BP>BP-BP

Answer 43

Number of closest neighbours surrounding an ion in a lattice structure Ionic radius

Answer 44

2BP Linear, 180 3BP Trigonal planar, 120 2BP, 1LP Bent, 117.5 4BP Tetrahedral 109.5 3BP, 1 LP Trigonal pyramidal, 107 2BP, 2 LP Bent, 104.5 5BP Trigonal bipyramidal, 120, 90 4BP, 1 LP See-saw shape, 117.5, <90 3BP, 2 LP T-shaped 115, <90 2BP, 3 LP Linear, 180 6BP Octahedral, 90 5BP, 1 LP **square pyramidal**, <90 4BP, 2 LP **square planar**, <90

Answer 45

Electrolytic cell: electric energy to chemical energy Electrochemical cell: chemical energy to electrical energy

Answer 46

Cathode: Place where reduction takes place Anode: Place where oxidation takes place Red cat and ox-an Electrochemical: Cathode +, anode - Electrolytic: Cathode -, anode +

Answer 47

Ion-ion (Pt electrode) Ion-metal (metal electrode, usually reactive) gas-ion (pt electrode)

Answer 48

To maintain electrical neutrality. Charges flow from salt bridge to 2 half cells to maintain charge balance. OR To act as electrical connector. Ions can flow through salt bridge to complete the circuit between the 2 half cells.

Answer 49

External circuit via connecting wires NOT through salt bridge

Answer 50

**concentrated** electrolyte

Answer 51

**Platinum electrode** in 1.0 mol/dm^-3 solution with H2 gas at 1 bar bubbled in at 298K

Answer 52

298K, **partial pressure of each gas is 1 bar**, concentration of all aqueous ions is 1.0 mol dm^-3 NB: pressure of **whole system** doesn’t have to be 1 bar

Answer 53

Potential difference between (M2+|M electrode) / (M3+/M2+| pt electrode) / (X/X-| Pt electrode) and standard hydrogen electrode at standard conditions of partial pressure of each gas at 1 bar, concentration of aq ions at 1.0 mol dm^-3 and temperature at 298K.

Answer 54

Tendency of half-cell to undergo reduction relative to the standard hydrogen electrode

Answer 55

change concentration of ions POE to shift left/right Reduction/oxidation pre-dominates Reduction potential (more/less positive/negative)

Answer 56

See which ions go cathode vs anode. Most + at cathode —> reduced; most - at anode —> oxidation E(cell) = E(red)- E(oxi)

Answer 57

<0 thermodynamically infeasible as written =0 reaction at eqm, not spontaneous in either direction >0 thermodynamically feasible as written

Answer 58

Might be thermodynamically feasible but not kinetically feasible Possible reasons: high Ea (strong covalent bonds require a lot of energy to break/similar charge ions require a lot of energy to overcome repulsion first) or very slow rate (unobservable in the short term) OR conditions non-standard. POE shift —> E and E cell shifts —> thermodynamically feasible under these conditions

Answer 59

ΔG = -nFE NB: Stoichiometric coefficient affects G (by affecting no. of moles of e transferred) but NOT E

Answer 60

T. As long as E +, thermodynamically spontaneous. Seen in electrolytic purification of copper

Answer 61

Standard electrode potential State of electrolyte (molten/aq) Nature of electrode (active/inactive) concentration of reactants (shift POE, E cell positive —> reaction spontaneous) [this one is the brine eg]

Answer 62

2H2O + 2e- —> H2 + 2OH- [R] 2Cl- —> Cl2 + 2e- [O] (Because of conc difference for cathode side, POE shift, E cell of Cl- can rise above that of H2O —> preferentially oxidised) Cathode: steel Anode: titanium Cats like to ‘steal’; can ‘titan’ ‘anot’

Answer 63

Brine: Manufacture chlorine from salt Anodising aluminium: Create an insoluble Al2O3 layer/thicken it around the aluminium object to resist corrosion and act as an electrical insulator Copper: To purify impure copper

Answer 64

2H2O —> O2+ 4H+ + 4e- [O] 4Al + 3O2 —> 2Al2O3 2H+ + 2e- —> H2 [R] Cathode: pt electrode Anode: aluminium object

Answer 65

Electrolysis of Brine: concentrated NaCl (aq) Anodising Aluminium: H2SO4 (aq) Electrolytic purification of copper: CuSO4 (aq)

Answer 66

Cu —> Cu2+ + 2e- [O] Zn —> Zn2+ + 2e- [O] Sn —> Sn2+ + 2e- [O] Fe —> Fe2+ + 2e- [O] Cu2+ + 2e- —> Cu [R] NB all the reactions above will happen and dissolve as ion. But those (metal ion|metal) with E value more than +0.34V will fall to the bottom (anode sludge). Cathode (pure) Anode (impure)

Answer 67

A particle (atom/molecule/ion) that has **at least** 1 unpaired electron.

Answer 68

Number of moles of electrons transferred to discharge one mole of ion at an electrode is equal to the number of charges on an ion.

Answer 69

Mass of a substance produced at an electrode during electrolysis is directly proportional to the amount of electricity passed.

Answer 70

Q = It Q = F x no. of moles of electrons One faraday = avogadro’s constant x charge of 1 electron (F=Le)

Answer 71

Set up electrolysis cell with CuSO4 (aq) as electrolyte and 2 Cu electrodes **of known mass*. Pass current of known I for a fixed period of time (t seconds) Remove electrodes and find gain in mass of cathode (m grams) (gain in mass at cathode should be same as loss in mass at anode) —> **wash, dry and re-weigh** Use m/63.5 to find number of moles of Cu Then use 2 x It/F to find number of moles of Cu (2 times the number of moles of electrons transferred) Solve for F Use equation L=F/e to find avogadro’s constant (L)

Answer 72

d-block element that is able to form one or more stable ions with partially filled d subshell.

Answer 73

Half and fully filled shells associated with higher stability as inter-electronic repulsion between 4s electrons are minimised

Answer 74

Roughly invariant NC increase (since protons increase) offset by increase in shielding effect since electrons added to penultimate 3d electron shell —> ENC roughly constant —> 1st IE roughly constant

Answer 75

Roughly invariant NC increase (since protons increase) offset by increase in shielding effect since electrons added to penultimate 3d electron shell —> ENC roughly constant —> 2nd IE roughly constant Except for Cu and Cr, because 2nd electron removed from inner 3d shell —> shielding effect much lower than other TM, ENC higher, eFOA stronger, more energy needed to remove 2nd valence e of Cr and Cu —> higher than expected 2nd IE

Answer 76

NC increase (since protons increase) but roughly constant shielding effect since all have some number of inner shell electrons —> ENC increases across the group —> 3rd IE increases across the group Anomaly: Fe; removal of 3rd electron is from 3d orbital with paired electrons (which experience repulsion) and would form a half-filled 3d subshell associated with higher stability —> eFOA between valence e and positive nucleus lower, much less energy needed to remove 3rd valence electron —> lower than 3rd IE of other TM

Answer 77

TM Higher More electrons can be delocalised per atom (4s and unpaired 3d can all be delocalised compared to only 4s electrons for s block metals so eFOA between sea of delocalised e and positive cations increased) —> more energy needed to overcome —> higher mp

Answer 78

TM higher Proton number higher —> NC higher and shielding effect lower (d orbitals more diffuse, shielding effect less effective for TM); ENC higher, eFOA between positively charged cations and valence electrons higher —> v e held closer to nucleus —> atomic radii and volume smaller Mass higher because atomic number is higher for TM Density = mass/volume; larger mass, smaller volume —> density higher

Answer 79

For TM, 4s and unpaired 3d can all be delocalised because 3d and 4s electrons are close in energy compared to only 4s electrons being delocalised for s block metals because 4s and 3p electrons vary greatly in energy Maximum oxidation state is sum of unpaired 3d electrons and 4s electrons.

Answer 80

Max os of Zn is +2 (has 0 unpaired 3d electrons, and 2 4s electrons)

Answer 81

Low OS: Ionic, basic High OS: Covalent, acidic High OS = higher polarising power (since charge density = charge/radius is higher) —> highly able to polarise electron cloud of anion and form high degree of covalent bonding

Answer 82

- carbon and iron atoms of different sizes —> lattice structure less orderly —> more difficult to displace without breaking metallic bonds/shattering lattice structure But also more brittle than iron Harder to displace but once lattice structure is no longer orderly they can’t easily slide over one another anymore —> more easily broken/shattered

Answer 83

Formation of chromium oxide so water can’t reach iron inside so can’t form rust

Answer 84

Ion-dipole! NOT just H bond!

Answer 85

Size of neighbouring atoms —> repulsion between electron cloud of neighbouring atoms (more significant for larger molecules) —> larger bond angle Electronegativity of atoms: central atom more electronegative —> pull lone pair of electrons towards the nucleus of the central atom —> more repulsion between electron pairs —> larger bond angle

Answer 86

Size of neighbouring atoms —> repulsion between electron cloud of neighbouring atoms (more significant for larger molecules) —> larger bond angle Electronegativity of atoms: central atom more electronegative —> pull lone pair of electrons towards the nucleus of the central atom —> more repulsion between electron pairs —> larger bond angle

Answer 87

Number of electrons/electron cloud size (affects polarisability and stuff) Degree of branching (affect extent of id-id formed)

Answer 88

Net dipole moment, affects strength of pd-pd

Answer 89

Extent of H bonds (no. Of H bonds per molecule) Dipole moment of H-X bond (where X=F/O/N) because affects the magnitude of the partial positive charge on H

Answer 90

All structures are SMS (covalent bonds within molecule with weak __ between molecules) In same period, idid gets stronger since size of electron cloud increases and higher polarisability of e cloud = higher extent of id-id = more energy needed to overcome = rising melting point BUT FON are highly electronegative, making the 3 molecules highly polar and held by H bonds —> stronger and require more energy to overcome —> higher than expected boiling points when compared to hydrides formed by other elements in their respective periods

Answer 91

Liquid, water interact in clusters, can form H bonds with 2 neighbouring water molecules H bonds constantly break and reform —>

Answer 92

Liquid, water interact in clusters, can form H bonds with 2 neighbouring water molecules H bonds constantly break and reform —> water molecules slide past each other easily vs solid, form H bonds w 4 others, tetrahedral arrangement —> rigid, highly ordered, open structure, **water molecules more spaced out** When ice melts, water molecules can move into the cavities of the ice structure —> increases number of water molecules per unit volume —> ice is denser

Answer 93

Only in non-polar solvent / gaseous phase 2 carboxylic acids with similar masses form intermolecular hydrogen bonds and bond together, hence exist as dimers Polar solvent, preferentially forms H bonds with much higher proportion of polar solvent molecules

Answer 94

Close proximity of ___ groups allows the molecules to experience intramolecular H bonds between them —> fewer sites available for formation of intermolecular H bonds —> extent of intermolecular H bonds less, less energy needed to overcome —> lower mp/bp

Answer 95

Energy released from the formation of ___ (in)sufficient to overcome energy that needs to be absorbed to overcome the ____ bonds.

Answer 96

GMS: insoluble in both GIS: Soluble in polar, insoluble in non-polar SMS: like dissolves like

Answer 97

Solid: particles are very close together, held in orderly arrangement, vibrate about their fixed positions Liquid: particles are close together and arranged in fairly orderly manner, but can vibrate, rotate and move through the liquid Gas: particles are far apart, mainly empty space between particles, move freely through the container with continuous random motion.

Answer 98

Perfectly elastic collisions (no loss of kinetic energy upon collision) Size and Volume of gas particles with respect to volume of container is negligible Intermolecular forces of attraction between gaseous atoms is negligible Ave KE of molecules proportional to temp (K) Applies to both: in continuous, rapid and random linear motion

Answer 99

High temp, low pressure

Answer 100

Number of molecules with given energy against energy ; area under curve must remain the same Peak shifts left, fraction of particles with lower energy increases, and fraction with higher energy decreases More particles with most probable energy and lower proportion at lower energy

Answer 101

At constant pressure, volume is directly proportional to temperature in Kelvin.

Answer 102

At constant temp, volume is inversely proportional to pressure of the gas.

Answer 103

At constant volume, pressure of the gas is directly proportional to temperature of the gas in kelvin.

Answer 104

Same volume of gases at same temp and pressure have the same number of particles.

Answer 105

Total pressure is the sum of partial pressures of all the gases in the system, provided that the gases do not react chemically.

Answer 106

Axes: PV/RT against external pressure Negative deviation: low external pressure, molecules about to strike the walls experience significant IMFOA to neighbouring molecules, reducing impact with which they hit the walls of the container. Observed pressure hence lower than expected, and PV/RT is less than expected —> negative deviation Positive deviation: at high external pressure, volume of molecules with respect to container no longer negligible, because they are pushed very close together and less compressible. Volume of observed gas is larger than ideal volume —> PV/RT larger than expected —> positive deviation.

Answer 107

Type of IMFOA (for negative deviation) Large/heavy/big gas particles (can use Mr to estimate)

Answer 108

Addition to pressure to correct for IMFOA and subtraction from volume to correct for molecular size

Answer 109

Negative: Exothermic, temperature rises, heat released, stability increases (energy level decreases) Positive: Endothermic, temperature falls, heat absorbed, stability decreases (energy level increases)

Answer 110

Always accompanied by balanced chemical eqn **with state symbols** yeah affected by ratio Yeah flip sign

Answer 111

Q = mc∆T =*p*vc∆T, (v here is the volume of the TOTAL liquid) ∆H = Q/amount of limiting reagent But then you needa use this value that you find to find like the different ∆H you need (eg neut, sol, etc.)

Answer 112

Add 2 solutions together, find max/min temp, use that to calculate the ∆H Precautions: cups must be good thermal insulators (eg styrofoam) as good thermal insulation and high specific heat capacity Limitations: does not take into consideration heat loss/heat gain from surroundings

Answer 113

Procedure 1. Using a 100cm^3 measuring cylinder, measure v cm^3 of solution 1 and transfer into a 250cm^3 beaker placed in a styrofoam cup to minimise heat loss to surroundings. 2. Using an electronic weighing balance, weigh the mass of the weighing bottle (m1), weighing bottle and about 5.0g of the solid (m2). 3. Place thermometer in beaker with substance 1 and start stopwatch. Record temperature at 0 minute. At regular intervals of 1 minute, record the temperature of the solution. 4. At 4 minute mark, pour solution 2/solid into the same beaker and stir continuously with a glass rod. Do not attempt to take the temperature at this point (temp changes too rapidly to get a steady/accurate reading) 5. Continue to record temperature at regular intervals of every minute from 5-12 minute mark. 6. Reweigh empty weighing bottle (m3) and take m3-m1 to get mass of solid reacted. Graph plotting: 1. Plot a graph of temperature against time 2. Draw a best fit line for all the points before solid was added (4 min mark) and another best fit line for all the points after solid was added (4 min mark). Extrapolate both lines (in DOTTED lines) so they cross at t=4 min. 3. Determine ∆T by finding temperature difference between 2 graphs at 4 minute mark. Calc: 1. Q = vc*p*∆T 2. n= (m3-m1)/molar mass = x 3. ∆H = Q/x

Answer 114

Energy absorbed when one mole of pure solid is formed from its constituent elements in standard state under standard conditions of 298K and 1 bar.

Answer 115

Can be positive or negative. Positive indicates that stability of system decreased (reactants more stable than products) but negative indicates that stability of system increased (products more stable than reactants).

Answer 116

Energy released when 1 mole of substance is completely burnt in excess oxygen under standard conditions of 298K and 1 bar.

Answer 117

Always negative. More energy released when strong covalent bonds within CO2 and H2O molecules are formed than energy absorbed from breaking of covalent bonds in reactant molecules because CO2 and H2O are very small molecules with high degree of orbital overlap (very effective) and hence very strong covalent bonds.

Answer 118

Enthalpy change of formation of MgO (s) Enthalpy change of combustion of Mg (s)

Answer 119

1/2 bond energy of F-F bond Enthalpy change of atomisation of F (g)

Answer 120

Enthalpy change of reaction is independent of pathway, provided that initial and final state of reaction is the same.

Answer 121

Combustion: reactant-product Bond energy: reactant-product Formation: product-reactant Derivation: write out the base equation for the larger compound (eg for formation the standard state stuff and for combustion the number of CO2 and H2O after etc…) then draw the born haber cycle and add in the missing components (eg enthalpy values and balancing of products/reactants)

Answer 122

Energy released when 1 mole of water is formed when an acid neutralises a base in an infinitely dilute aqueous solution under standard conditions of 298K and 1 bar.

Answer 123

Energy released when 1 mole of water is formed when an acid neutralises a base in an infinitely dilute aqueous solution under standard conditions of 298K and 1 bar.

Answer 124

Heat is always evolved due to formation of bonds between H+ and OH- to form H2O molecules. Always a fixed value as strong acids and bases undergo full dissociation hence all their neutralisation reactions can be simplified to the same equation: H+ + OH- —> H2O

Answer 125

Strong acids and bases, full dissociation. Weak acids and bases, only partial dissociation. Hence additional energy needed to be absorbed to ionise the weak acid/base before complete neutralisation can take place, hence less exothermic ∆H(Neut).

Answer 126

Energy absorbed when one mole of electrons is removed from one mole of gaseous atoms to form one mole of singly positive gaseous ions. … Energy absorbed when one mole of electrons is removed from one mole singly positive gaseous ions to form one mole of doubly positive gaseous ions.

Answer 127

Energy released when 1 mole of ionic solid is formed from isolated gaseous ions from an infinite distance apart.

Answer 128

Always negative Energy released from the formation of strong ionic bonds between oppositely charged ions.

Answer 129

Ie factors affecting LE Quote formula of LE Charge and radius; since it affects magnitude of LE which affects bond strength And another one is crystal structure (In enthalpy notes); arrangement of ions affects attraction and repulsion between ion in the compound

Answer 130

higher magnitude of LE = stronger ionic bonds = more energy needed to overcome stronger ionic bonds = higher mp/bp But also, Larger LE = products more stable

Answer 131

Energy absorbed to break 1 mole of covalent bonds between 2 atoms in a gaseous molecule.

Answer 132

If in solid state, energy also absorbed for sublimination of the object, so it’s not reflective of the true energy to just break the bond.

Answer 133

Energy absorbed to break bonds

Answer 134

1. Average values, not specific to the bond for the specific molecule 2. Only for molecules in gaseous state

Answer 135

Energy absorbed to form 1 mole of isolated gaseous atoms from constituent elements in standard state under standard conditions of 298K and 1 bar.

Answer 136

Energy has to be absorbed so that atoms can break away from rigid structures in other physical states/break covalent bonds to liberate atoms

Answer 137

Enthalpy change when one mole of atoms or anions gains one mole of electrons.

Answer 138

Enthalpy change when one mole of atoms or anions gains one mole of electrons.

Answer 139

1st: negative; eFOA formed when highly positive nucleus attracts the incoming electrons, releasing energy 2nd onwards: positive; energy needs to be absorbed to overcome repulsion between increasingly negatively charged anion and incoming negatively charged electrons.

Answer 140

Energy profile: y - energy/KJ mol^-1; x - progress of reaction Energy level: y - energy/KJ mol^-1

Answer 141

Energy profile: y - energy/KJ mol^-1; x - progress of reaction Energy level: y - energy/KJ mol^-1

Answer 142

Energy released when 1 mole of **gaseous ions** is dissolved in a large amount of water under standard conditions of 298K and 1 bar. NO isolated! (isolated is ALe, infinite is LeNS)

Answer 143

Formation of ion-dipole interactions releases a lot of energy (sufficient to overcome energy absorbed from breaking of H bonds between water molecules) Same type of ions NO interactions between them k!

Answer 144

Formation of ion-dipole interactions releases a lot of energy (sufficient to overcome energy absorbed from breaking of H bonds between water molecules and weak IMFOA between ions)

Answer 145

eFOA between ions and opposite partial charges. (Like btw cation and partial negative charge and anion and partial positive charge)

Answer 146

Charge density, higher charge density = strong ion-dipole interactions = more exorthermic ∆H(Hyd)

Answer 147

Enthalpy change when one mole of solute is completely dissolved in excess solvent to form an infinitely dilute solution under standard conditions of 298K and 1 bar.

Answer 148

∆H (sol) = ∆H (Hyd) - ∆H (LE) ; solid ionic compound —> isolated aq ions Energy absorbed when ionic bonds in solid lattice structure have to be broken (ions separated) (-LE) and interaction between solvent molecules and solute molecules are broken Energy released when ion-dipole interactions between water molecules and liberated ions are formed (H)

Answer 149

Hydroxides: solubility increases - H by hydroxide no change, but by cation less exothermic since radius increasing. - LE becomes less exothermic because radius increasing significantly since radius of OH- is so small. - Fall in magnitude of H much more significant than fall in magnitude of LE since r- is so small —> S becomes more exothermic —> solubility increases Sulfates: solubility decreases. - H directly proportional to charge density. (H by sulfate no change, but H by cation less exothermic because radius increasing; charge density directly proportional to charge/radius) - LE roughly constant because sulfate so much bigger than metal ion - S = H-LE —> S becomes more positive —> solubility decreases)

Definitions Flashcards

(174 cards)