Chemistry Paper 2 June 2011

1. A$1.4 \times 10^{-2}$
2. B$7.0 \times 10^{-4}$
3. C$1.4 \times 10^{-3}$
4. D$2.8 \times 10^{-3}$

1. A2.55
2. B11.15
3. C11.45
4. D12.00

1. Abarium hydroxide crystals
2. Bbarium carbonate
3. Cbarium oxide
4. Dbarium sulphate

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1. A$3.9 \times 10^{-6}\ mol^2\,dm^{-6}$
2. B$3.1 \times 10^{-5}\ mol^4\,dm^{-12}$
3. C$2.7 \times 10^{-9}\ mol^3\,dm^{-9}$
4. D$1.1 \times 10^{-8}\ mol^3\,dm^{-9}$

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1. Ait reacts slowly with atmospheric nitrogen gas, forming a layer of calcium nitride across the exposed surface.
2. Bit absorbs $CO_2$ from the air, precipitating white $CaCO_3$ and turning the solution milky.
3. Cit absorbs oxygen from the air, forming calcium peroxide crystals across the exposed surface.
4. Dit evaporates faster than it can absorb moisture, leaving behind white calcium hydroxide crystals.

1. Agreen to orange
2. Byellow to orange
3. Corange to green
4. Dorange to colourless

1. A$2.32 \times 10^{-4}$
2. B$1.16 \times 10^{-5}$
3. C$5.80 \times 10^{-5}$
4. D$1.16 \times 10^{-4}$

1. A$SO_2 + Cr_2O_7^{2-} \rightarrow 2Cr^{3+} + SO_4^{2-}$
2. B$SO_2 + Cr_2O_7^{2-} + 2H^+ \rightarrow 2Cr^{3+} + SO_3^{2-} + H_2O$
3. C$3SO_2 + Cr_2O_7^{2-} \rightarrow 2Cr^{3+} + 3SO_4^{2-}$
4. D$3SO_2 + Cr_2O_7^{2-} + 2H^+ \rightarrow 2Cr^{3+} + 3SO_4^{2-} + H_2O$

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1. Aa green gas is evolved
2. Breddish-brown fumes are evolved
3. Cmisty white fumes only
4. Da yellow precipitate

1. Achlorine is a stronger oxidising agent than sulphuric acid
2. Bthe chloride ion is too weak a reducing agent to be oxidised
3. Chydrogen chloride is insoluble in the acid
4. Dsodium chloride is not an ionic compound

1. A$Cl_2 + 2NaOH \rightarrow NaCl + NaOCl + H_2O$
2. B$Cl_2 + 2NaOH \rightarrow 2NaCl + H_2O + \frac{1}{2}O_2$
3. C$Cl_2 + NaOH \rightarrow NaCl + HOCl$
4. D$3Cl_2 + 6NaOH \rightarrow 5NaCl + NaClO_3 + 3H_2O$

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1. Ait forms an insoluble precipitate with dissolved minerals, removing them from the water.
2. Bit displaces dissolved oxygen from the water, starving microorganisms of oxygen.
3. Cit raises the pH of the water, making it too alkaline for microorganisms to survive.
4. Dit reacts with water to form HOCl, a strong oxidising agent that kills microorganisms.

1. Achlorine lowers the pH of the dye solution so much that the dye itself turns colourless.
2. Bchlorine forms an insoluble, colourless precipitate by binding directly onto the dye molecule.
3. Cchlorine reacts with water to form HOCl, which oxidises and so destroys the coloured dye molecules.
4. Dchlorine directly substitutes into the dye molecule itself, physically removing its coloured group.

1. Aconcentrated $HNO_3$ and concentrated $H_2SO_4$ at about 55 °C
2. Bdilute $HNO_3$ at room temperature
3. C$NaNO_2$ and dilute HCl below 10 °C
4. Dconcentrated $HNO_3$ with an aluminium chloride catalyst

1. A4-position, because the ester group is 2,4-directing
2. B1-position, replacing the ester group
3. C3-position, because the ester group is deactivating and 3-directing
4. D2-position, because the ester group is activating

1. Areduces the ketone to a secondary alcohol
2. Bcleaves the ring at the double bond
3. Cadds hydrogen across the $C=C$ bond
4. Doxidises the ketone to a carboxylic acid

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1. Areduces the ketone group to a secondary alcohol, leaving the $C=C$ bond in ring A untouched.
2. Boxidatively cleaves the ring A carbon-carbon double bond, giving carbonyl/carboxylic products.
3. Chydrogenates the carbon-carbon double bond, adding hydrogen across it without breaking the ring.
4. Dhas no effect, since testosterone contains no carbon-carbon double bond for it to react with.

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1. Aa zwitterion held by strong ionic attractions
2. Ba non-polar molecule
3. Chydrogen bonded dimers
4. Da covalent macromolecule

1. Ait is completely non-polar
2. Bit reacts with water to form a salt
3. Cit exists as a zwitterion in solution
4. Dthe $-CO_2H$ group hydrogen bonds to water but the benzene ring does not

1. Aare largely non-polar and attract one another only weakly
2. Bhave a very high relative molecular mass
3. Care held together by ionic bonds
4. Dform very strong hydrogen bonds with one another

1. Ait forms hydrogen bonds between its own molecules more strongly than the other two substances do.
2. Bits far larger relative molecular mass alone accounts for the extra thermal energy needed to melt it.
3. Cit exists as a zwitterion, so strong ionic attractions hold its crystal lattice together.
4. Dit forms a covalent network solid, similar to diamond, spanning the entire crystal structure.

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