Chemistry Paper 2 November 2008

1. A63 kJ
2. B630 kJ
3. C0.63 kJ
4. D6.3 kJ

1. A1458 kJ
2. B2016 kJ
3. C6300 kJ
4. D146 kJ

1. A$C_4H_9OH(l) + 5O_2(g) \rightarrow 4CO_2(g) + 5H_2O(l)$
2. B$C_4H_9OH(l) + 6O_2(g) \rightarrow 4CO_2(g) + 5H_2O(l)$
3. C$2C_4H_9OH(l) + 9O_2(g) \rightarrow 8CO_2(g) + 10H_2O(l)$
4. D$C_4H_9OH(l) + 4O_2(g) \rightarrow 4CO_2(g) + 5H_2O(l)$

1. AStandard enthalpy of combustion is the enthalpy released when one mole of a substance dissolves completely in water at room temperature and pressure; the experimental value differs mainly because the water used to absorb the heat was not sufficiently pure.
2. BStandard enthalpy of combustion is the enthalpy change when one mole of a substance reacts completely with hydrogen gas under standard conditions of temperature and pressure; the experimental value differs mainly because the reaction proceeded far too quickly to measure accurately.
3. CStandard enthalpy of combustion is the enthalpy change when one mole of a substance is completely burned in oxygen under standard conditions (298 K, 100 kPa); the experimental value differs because it was not measured under standard conditions and heat was lost to the surroundings.
4. DStandard enthalpy of combustion is the enthalpy change when any convenient amount of a substance burns partially in air at any temperature and pressure; the experimental value differs mainly because too little butanol was actually weighed out before burning began.

1. Athe water used was distilled rather than ordinary tap water, which by itself has no measurable effect on the amount of heat released during combustion
2. Bthe burner flame appeared blue rather than yellow throughout the experiment, which by itself indicates that essentially none of the heat produced was lost to the surroundings
3. Cthe thermometer used was calibrated in Fahrenheit instead of Celsius, which would make the numerical value of the recorded temperature rise appear larger than it actually should be
4. Dincomplete combustion of the butanol, and evaporation of butanol before it burned; both cause the calculated enthalpy of combustion to be lower than the true value

1. A0
2. B1
3. C2
4. D3

1. Arate $= k[H_2][NO]^2$
2. Brate $= k[H_2]^2[NO]^2$
3. Crate $= k[H_2][NO]$
4. Drate $= k[H_2]^2[NO]$

1. A$0.024\ s^{-1}$
2. B$0.024\ mol^{-1}dm^3s^{-1}$
3. C$0.024\ mol\,dm^{-3}s^{-1}$
4. D$0.024\ mol^{-2}dm^6s^{-1}$

1. Athe number of distinct elementary steps making up the overall reaction mechanism, as deduced from the proposed pathway; overall order = 1
2. Bthe sum of the powers to which the reactant concentrations are raised in the experimentally-determined rate equation; overall order = 3
3. Cthe number of molecules that must collide simultaneously, in the correct orientation, for the reaction to occur at all; overall order = 3
4. Dthe sum of the powers to which the reactant concentrations are raised in the experimentally-determined rate equation, read directly off the balanced stoichiometric equation; overall order = 2

Answer this when you sit the paper.

1. A$Ca(s) + 2H_2SO_4(aq) \rightarrow Ca(SO_4)_2(s) + 2H_2(g)$
2. B$Ca(s) + H_2SO_4(aq) \rightarrow CaSO_4(s) + H_2(g)$
3. C$Ca(s) + H_2SO_4(aq) \rightarrow CaSO_3(s) + H_2O(l)$
4. D$2Ca(s) + H_2SO_4(aq) \rightarrow Ca_2SO_4(s) + H_2(g)$

1. Adecreases, because the hydration enthalpy falls faster than the lattice enthalpy
2. Bstays the same, because all are ionic
3. Cincreases, because the cations become larger
4. Dincreases, because the lattice enthalpy falls

1. Aglass
2. Bfertilisers
3. Cplaster of Paris
4. Dwashing soda

1. Athe hydration enthalpy of the cation decreases more rapidly than the lattice enthalpy as the group is descended, making dissolution less energetically favourable.
2. Bthe lattice enthalpy decreases more rapidly than the hydration enthalpy of the cation as the group is descended, making dissolution thermodynamically more favourable overall.
3. Cthe anion becomes smaller relative to the cation as the group is descended, which strengthens the ionic lattice and reduces solubility markedly.
4. Dthe sulphate ion becomes progressively less able to form hydrogen bonds with the surrounding water molecules as the group is descended.

1. A$1s^22s^22p^63s^23p^63d^8$
2. B$1s^22s^22p^63s^23p^64s^23d^4$
3. C$1s^22s^22p^63s^23p^63d^64s^2$
4. D$1s^22s^22p^63s^23p^63d^54s^1$

1. A$+3$ and $+6$
2. B$+1$ and $+2$
3. C$+2$ and $+3$
4. D$+2$ and $+6$

1. Ais used up during the reaction
2. Balters the position of equilibrium
3. Cis in the same phase as the reactants
4. Dis in a different phase from the reactants

1. Aa d-block element that forms at least one stable ion with a partially filled d subshell; they have variable oxidation states that provide alternative reaction pathways, and partially filled d orbitals that adsorb reactant molecules onto their surface.
2. Bany element found anywhere in the d-block, regardless of the ions it is able to form under any circumstances; such elements are effective catalysts mainly because they have unusually high melting points and very large atomic radii that increase surface area.
3. Ca d-block element that forms at least one stable ion with a partially filled d subshell; however, these elements are effective catalysts mainly because they have unusually low densities and weak metallic bonding that speeds up surface reactions.
4. Dan s-block element with exactly two outer electrons is classed as a transition element; such elements are effective catalysts mainly because they adopt fixed oxidation states and have completely filled d orbitals that repel reactant molecules.

1. Aa glycosidic link
2. Ban ester link
3. Can ether link
4. Da peptide link

1. A1,6-diaminohexane and hexanedioic acid
2. Bethane-1,2-diol and hexanedioic acid
3. C1,6-diaminohexane and benzene-1,4-dicarboxylic acid
4. Daminohexanoic acid only

1. Amade from one type of monomer only
2. Bmade from two or more different monomers
3. Cformed by addition polymerisation only
4. Dcross-linked between its chains

1. Aaddition polymerisation only, with no small molecule lost; glycosidic bond
2. Baddition polymerisation only, with no small molecule lost; peptide bond
3. Ccondensation polymerisation, with water eliminated; ester bond
4. Dcondensation polymerisation, with water eliminated; peptide bond

1. A$2HNO_3 \rightarrow 2NO_2^+ + O_2 + 2e^-$
2. B$HNO_3 \rightarrow NO_2^+ + OH^-$
3. C$HNO_3 + H_2SO_4 \rightarrow NO_2^+ + HSO_4^- + H_2O$
4. D$HNO_3 + 2H_2SO_4 \rightarrow NO_2^+ + 2HSO_4^- + H_3O^+$

1. Aelectrophilic addition
2. Bfree radical substitution
3. Celectrophilic substitution
4. Dnucleophilic substitution

1. A3-aminobenzoic acid
2. B3-nitrobenzoic acid
3. C3-nitrobenzaldehyde
4. D3-nitrophenol

1. Aconc. $HNO_3$ alone at 100 °C with no catalyst; acidified $K_2Cr_2O_7$ under reflux; heated strongly under reflux
2. Bconc. $HNO_3$/conc. $H_2SO_4$ at about 55 °C; acidified $KMnO_4$ under reflux; room temperature
3. Cdilute $HNO_3$ alone at room temperature; acidified $KMnO_4$ under reflux; heated strongly under reflux
4. Dconc. $HNO_3$/conc. $H_2SO_4$ at about 55 °C; cold dilute $KMnO_4$ with no heating; room temperature

1. Ahydrolysis; esterification
2. Bsubstitution; elimination
3. Creduction; oxidation
4. Doxidation; reduction

Answer this when you sit the paper.