Chemistry Paper 2 June 2013

1. Athe concentrations of reactants and products are equal
2. Bthe reaction goes to completion
3. Cboth reactions have stopped
4. Dthe forward and reverse reactions occur at the same rate

1. Athe temperature of the drink falls
2. Bthe drink reacts with the glass
3. Cthe pressure above the liquid falls, shifting the equilibrium to the left
4. Dthe solubility of carbon dioxide increases

1. Athe intensity of the purple iodine colour increases with time
2. Bhydrogen iodide is a coloured gas
3. Cthe total pressure changes as the reaction proceeds
4. Dhydrogen absorbs ultraviolet light

1. Areacts the dissolved $CO_2$ permanently with water to form solid carbonic acid crystals.
2. Breduces the frequency of collisions between $CO_2$ molecules and the liquid surface, trapping more gas inside the sealed container.
3. Clowers the temperature of the liquid enough to increase the solubility of the dissolved gas, independent of any equilibrium shift.
4. Dshifts the equilibrium position to the right (Le Chatelier's principle), increasing the amount of dissolved $CO_2$.

1. Ahas no effect on rate at all, since pressure only affects equilibria involving a change in the number of gas moles.
2. Bincreases only the rate of the forward reaction, shifting the equilibrium position towards more $H_2$ and $I_2$ being formed overall.
3. Cincreases the rate of both forward and reverse reactions, since particles collide more frequently.
4. Ddecreases the rate of both reactions, since the gas molecules have less room to move around and collide with one another.

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1. Astops the reaction completely and permanently, regardless of how much the temperature is later raised again afterwards.
2. Bdecreases the rate of reaction, since fewer molecules have enough energy to react successfully.
3. Cincreases the rate of reaction, since cooler gas molecules collide more frequently and more energetically with each other.
4. Dhas no effect on rate, since temperature only shifts the equilibrium position rather than changing the rate itself.

1. Aa saturated calomel electrode
2. Ba copper electrode in copper(II) sulphate
3. Ca platinum electrode in pure water
4. Dthe standard hydrogen electrode

1. Ais a good reducing agent
2. Bdissolves slowly in the electrolyte
3. Chas the highest melting point of the metals
4. Dis inert and has a large surface area

1. Aapply only to reactions in the gas phase
2. Bcannot be measured for transition elements
3. Cgive no information about the rate of the reaction
4. Dchange with the size of the electrodes used

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1. Aa much weaker $X-X$ bond than chlorine
2. Ba larger atomic radius than chlorine
3. Ca lower electronegativity than chlorine
4. Da higher boiling point than chlorine

1. Aform weaker covalent bonds
2. Bbecome larger and more shielded, so attract an electron less strongly
3. Cbecome more electronegative
4. Dhave fewer electrons in the outer shell

1. Ahas a very high bond enthalpy
2. Bhas an unpaired electron
3. Cis much larger than the oxygen molecule
4. Dis highly polar

1. Ainstantly and completely at room temperature, forming a stable white solid product that does not decompose again.
2. Bslowly and reversibly, giving an equilibrium mixture far from complete, because the $H-I$ bond formed is comparatively weak.
3. Cexplosively, even in the dark, because the $H-I$ bond formed is exceptionally strong compared with the other hydrogen halides.
4. Dnot at all under any laboratory conditions available, since iodine is far too unreactive to combine with hydrogen gas.

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1. Aincreases, because the van der Waals forces between molecules increase as the molecules get larger, with more electrons.
2. Bstays roughly constant, since intermolecular forces do not depend on molecular size for non-polar molecules.
3. Cdecreases, because the covalent bond within each diatomic molecule becomes weaker and easier to break.
4. Ddecreases, because the van der Waals forces between molecules increase as the molecules get larger, with more electrons.

1. Anitrate contamination of drinking water, and loss of fish stocks through deoxygenation of the water.
2. Bacidification of rainwater across the region, and a reduction in the nitrogen content of harvested crops.
3. Ca rise in the price of nitrate fertiliser, and a shortage of usable farmland available for growing future crops.
4. Dan increase in dissolved oxygen in rivers, and a boost in fish stocks available as a food source for people.

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1. Afluorine's very high electronegativity pulls all of the shared electron density away from the bond entirely, leaving nothing shared.
2. Bthe small fluorine atoms' lone pairs repel each other strongly at close range, weakening the F-F bond.
3. Cthe F-F bond is largely ionic rather than covalent in character, so there is no true covalent bond present to measure.
4. Deach fluorine atom holds an unpaired electron in isolation, so no full covalent bond ever fully forms between the two atoms.

1. Aoxidation
2. Bhydrolysis
3. Can acid-base reaction
4. Delectrophilic addition

1. Aa soluble ammonium salt
2. Ban amide
3. Ca diazonium salt
4. Da chloroalkane

1. Aelectrophilic addition
2. Belectrophilic substitution
3. Cnucleophilic substitution
4. Dfree radical substitution

1. Acarboxylic acid
2. Bether linkage (C-O-C)
3. Ctertiary amine group
4. Dalkene (C=C) double bond

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1. Aesterification
2. Bnucleophilic substitution
3. Cacid-base (neutralisation)
4. Delectrophilic addition

1. Aa white precipitate forms
2. Bthe solution turns from green to orange
3. Ca gas is evolved which turns limewater milky
4. Dthe solution turns from orange to green

1. Athe mixture turns violet
2. Bsteamy white fumes of hydrogen chloride are evolved
3. Cno visible change occurs
4. Da yellow precipitate forms

1. Aas solvents and as flavourings
2. Bas fertilisers and as catalysts
3. Cas disinfectants and as refrigerants
4. Das fuels and as bleaches

1. Athe solution turns from colourless to a deep, permanent shade of blue almost immediately after mixing.
2. Ba colourless gas is evolved from the mixture, which turns limewater milky when tested afterwards.
3. Cthe orange bromine solution decolourises and a white precipitate also forms.
4. Da yellow precipitate forms, though the orange bromine colour itself stays completely unchanged.

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1. Aa colour change from colourless to deep purple, with no gas evolved
2. Bsteamy/misty white fumes of hydrogen chloride gas are given off
3. Ca green precipitate forms slowly over several minutes
4. Dthe mixture bubbles vigorously, releasing a colourless, odourless gas that relights a glowing splint