Danho
ZIMSEC A Level · J2012

Chemistry Paper 2 June 2012

Questions
37
Total marks
58
Time allowed
75 min

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Questions
37
Pass mark
23
Sit this paper

Answer every question in the printed order, get marked at the end, then see the answers.

The questions

Question 101

[1 marks]acids and bases / equilibria
A Bronsted-Lowry acid is a species which
  1. Aproduces hydroxide ions in water
  2. Bdonates a proton
  3. Caccepts a proton
  4. Ddonates a pair of electrons

Question 102

[1 marks]acids and bases / equilibria
The KaK_a expression for chloroethanoic acid, CH2ClCOOHCH_2ClCOOH, is
  1. A[CH2ClCOO−][H+][CH_2ClCOO^-][H^+]
  2. B[CH2ClCOO−][H+][CH2ClCOOH]\frac{[CH_2ClCOO^-][H^+]}{[CH_2ClCOOH]}
  3. C[CH2ClCOO−][CH2ClCOOH]\frac{[CH_2ClCOO^-]}{[CH_2ClCOOH]}
  4. D[CH2ClCOOH][CH2ClCOO−][H+]\frac{[CH_2ClCOOH]}{[CH_2ClCOO^-][H^+]}

Question 103

[1 marks]acids and bases / equilibria
Chloroethanoic acid is a stronger acid than ethanoic acid because the chlorine atom
  1. Awithdraws electrons and stabilises the anion formed
  2. Bincreases the relative molecular mass
  3. Cforms hydrogen bonds with water
  4. Dreleases electrons towards the −COOH-COOH group

Question 104

[2 marks]acids and bases / equilibria
In the reaction CH3COOH+H2O⇌CH3COO−+H3O+CH_3COOH + H_2O \rightleftharpoons CH_3COO^- + H_3O^+, identify the two conjugate acid-base pairs.

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Question 105

[2 marks]acids and bases / equilibria
In the reaction HCl+NH3→NH4++Cl−HCl + NH_3 \rightarrow NH_4^+ + Cl^-, identify the two conjugate acid-base pairs.

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Question 106

[1 marks]acids and bases / equilibria
A solution obtained by mixing chloroethanoic acid with sodium chloroethanoate is called a

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Question 107

[2 marks]acids and bases / equilibria
0.01 mol dm−30.01\ mol\,dm^{-3} chloroethanoic acid was mixed with 0.0002 mol dm−30.0002\ mol\,dm^{-3} sodium chloroethanoate. Given KaK_a for chloroethanoic acid =1.4×10−3 mol dm−3= 1.4\times10^{-3}\ mol\,dm^{-3}, calculate the pH of the mixture.

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Question 201

[1 marks]atomic structure / bonding
For an element C there is a very large jump between the seventh and eighth ionisation energies. Element C belongs to
  1. AGroup VII
  2. BGroup II
  3. CGroup IV
  4. DGroup VI

Question 202

[1 marks]atomic structure / bonding
Using the electron pair repulsion theory, the shape of the PCl3PCl_3 molecule is
  1. Atetrahedral
  2. Bpyramidal
  3. CT-shaped
  4. Dtrigonal planar

Question 203

[1 marks]atomic structure / bonding
The first ionisation energy decreases down a group of the Periodic Table because
  1. Athe nuclear charge decreases
  2. Bthe outer electrons are more strongly held
  3. Cthe atoms become more electronegative
  4. Dthe atomic radius and the shielding both increase

Question 204

[2 marks]atomic structure / bonding
Ionisation energy is defined as the energy required to
  1. Aremove one mole of electrons from one mole of gaseous molecules, breaking every covalent bond within them.
  2. Bremove one mole of electrons from one mole of gaseous atoms, forming one mole of gaseous 1+ ions.
  3. Cremove one electron from a single gaseous atom, forming a stable solid ionic lattice structure.
  4. Dadd one mole of electrons to one mole of gaseous atoms, forming one mole of gaseous 1- ions.

Question 205

[2 marks]atomic structure / bonding
Across a period of the Periodic Table, the first ionisation energy generally increases from left to right mainly because
  1. Athe atomic radius decreases across the period, but shielding also decreases at exactly the same rate, so the two effects should cancel each other out.
  2. Bthe nuclear charge increases while shielding from inner electrons stays roughly constant, so the outer electrons are pulled in more strongly.
  3. Cthe number of electron shells increases by one for each successive element across the period.
  4. Dthe outer electrons pair up within the same orbital, making each one easier to remove than the last.

Question 206

[1 marks]atomic structure / bonding
Using the electron pair repulsion theory, predict the shape of the PCl5PCl_5 molecule.

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Question 207

[1 marks]atomic structure / bonding
In PCl3PCl_3, how many non-bonding (lone) pairs of electrons does the central phosphorus atom have?

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Question 208

[1 marks]atomic structure / bonding
In PCl3PCl_3, phosphorus has 3 bonding pairs and 1 lone pair. The arrangement of these four electron pairs around phosphorus (ignoring whether each pair is bonding or lone) is

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Question 301

[1 marks]periodicity / solubility product
The electronic configuration of magnesium is
  1. A1s22s22p63s21s^22s^22p^63s^2
  2. B1s22s22p63s23p11s^22s^22p^63s^23p^1
  3. C1s22s22p61s^22s^22p^6
  4. D1s22s22p63s11s^22s^22p^63s^1

Question 302

[1 marks]periodicity / solubility product
The magnesium compound used in antacids reacts with stomach acid as
  1. AMg+2HCl→MgCl2+H2Mg + 2HCl \rightarrow MgCl_2 + H_2
  2. BMgCO3+HCl→MgCl2+CO2MgCO_3 + HCl \rightarrow MgCl_2 + CO_2
  3. CMg(OH)2+2HCl→MgCl2+2H2OMg(OH)_2 + 2HCl \rightarrow MgCl_2 + 2H_2O
  4. DMgO+HCl→MgCl+H2OMgO + HCl \rightarrow MgCl + H_2O

Question 303

[1 marks]periodicity / solubility product
Equal volumes of 1×10−2 mol dm−31 \times 10^{-2}\ mol\,dm^{-3} Ca2+Ca^{2+} and SO42−SO_4^{2-} solutions are mixed. Given Ksp(CaSO4)=2×10−5 mol2dm−6K_{sp}(CaSO_4) = 2 \times 10^{-5}\ mol^2dm^{-6},
  1. Ano precipitate forms, since the ionic product is 2.5×10−52.5 \times 10^{-5}
  2. Ba precipitate forms, since the ionic product is 1.0×10−41.0 \times 10^{-4}
  3. Cno precipitate forms, since the ionic product is 5.0×10−65.0 \times 10^{-6}
  4. Da precipitate forms, since the ionic product is 2.5×10−52.5 \times 10^{-5}

Question 304

[3 marks]periodicity / solubility product
Write a balanced equation, with state symbols, for the reaction between magnesium and steam.

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Question 305

[2 marks]periodicity / solubility product
Magnesium also reacts slowly with cold water (rather than steam), giving a different pair of products. Write the balanced equation for this reaction.

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Question 306

[1 marks]periodicity / solubility product
Name the magnesium compound commonly used, in over-the-counter remedies, to treat acid indigestion.

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Question 307

[1 marks]periodicity / solubility product
Write the solubility product, KspK_{sp}, expression for calcium sulphate.

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Question 401

[1 marks]organic chemistry / carbonyl compounds
Compounds Q and R contain 66.6 % carbon, 11.2 % hydrogen and 22.2 % oxygen by mass and have MrM_r = 72. Their molecular formula is
  1. AC5H12OC_5H_{12}O
  2. BC3H4O2C_3H_4O_2
  3. CC4H8O2C_4H_8O_2
  4. DC4H8OC_4H_8O

Question 402

[1 marks]organic chemistry / carbonyl compounds
Compound R, C4H8OC_4H_8O, gives a yellow precipitate with alkaline aqueous iodine but does not react with Fehling's solution. R is
  1. Abutan-2-ol
  2. Bbutanoic acid
  3. Cbutanone
  4. Dbutanal

Question 403

[1 marks]organic chemistry / carbonyl compounds
Butanone is reduced by sodium tetrahydridoborate. The organic product is
  1. Abutan-1-ol
  2. Bbutanal
  3. Cbutane
  4. Dbutan-2-ol

Question 404

[1 marks]organic chemistry / carbonyl compounds
Compound Q, C4H8OC_4H_8O, gives a positive (brick-red precipitate) result with Fehling's solution but does not react with alkaline aqueous iodine. Q is
  1. Abutanal, since aldehydes reduce Fehling's solution but Q gives no reaction with alkaline iodine.
  2. Bbutan-2-ol, since secondary alcohols are readily oxidised by the copper(II) ions present in Fehling's solution.
  3. Cbutanoic acid, since carboxylic acids also reduce Fehling's solution by donating a proton to it.
  4. Dbutanone, since ketones give a positive Fehling's test result in the same way that aldehydes do.

Question 405

[3 marks]organic chemistry / carbonyl compounds
R, butanone (CH3COCH2CH3CH_3COCH_2CH_3), reacts with excess alkaline aqueous iodine to give a yellow precipitate of triiodomethane (iodoform). The balanced equation for this reaction is
  1. ACH3COCH2CH3+3I2+4NaOH→CHI3+CH3CH2CH2OH+3NaI+3H2OCH_3COCH_2CH_3 + 3I_2 + 4NaOH \rightarrow CHI_3 + CH_3CH_2CH_2OH + 3NaI + 3H_2O
  2. BCH3COCH2CH3+3Cl2+4NaOH→CHCl3+CH3CH2COONa+3NaCl+3H2OCH_3COCH_2CH_3 + 3Cl_2 + 4NaOH \rightarrow CHCl_3 + CH_3CH_2COONa + 3NaCl + 3H_2O
  3. CCH3COCH2CH3+3I2+4NaOH→CHI3+CH3CH2COONa+3NaI+3H2OCH_3COCH_2CH_3 + 3I_2 + 4NaOH \rightarrow CHI_3 + CH_3CH_2COONa + 3NaI + 3H_2O
  4. DCH3COCH2CH3+I2+NaOH→CHI3+CH3CH2COONa+NaI+H2OCH_3COCH_2CH_3 + I_2 + NaOH \rightarrow CHI_3 + CH_3CH_2COONa + NaI + H_2O

Question 406

[1 marks]organic chemistry / carbonyl compounds
Q and R are isomers of C4H8OC_4H_8O, one an aldehyde and the other a ketone. Both aldehydes and ketones are, as a class, called

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Question 501

[1 marks]organic chemistry / functional groups
The functional groups present in cholic acid are
  1. Ahydroxyl and carboxylic acid
  2. Bketone and ester
  3. Caldehyde and hydroxyl
  4. Dcarboxylic acid and amide

Question 502

[1 marks]organic chemistry / functional groups
Cholic acid is warmed with ethanol in the presence of a little concentrated sulphuric acid. The organic product is
  1. Aan alkene
  2. Ban aldehyde
  3. Ca ketone
  4. Dan ester

Question 503

[1 marks]organic chemistry / functional groups
Progesterone contains a carbon-carbon double bond but cholic acid does not. The reagent which distinguishes them is
  1. Asodium metal
  2. Baqueous sodium carbonate
  3. Caqueous bromine
  4. D2,4-dinitrophenylhydrazine

Question 505

[2 marks]organic chemistry / functional groups
Treating cholic acid with NaBH4NaBH_4 in methanol gives
  1. Areduction of the −COOH-COOH group to an aldehyde, leaving the ring −OH-OH groups completely untouched.
  2. Bformation of an ester between the −COOH-COOH group and the methanol solvent.
  3. Cno visible reaction, because cholic acid has no ketone or aldehyde group for NaBH4NaBH_4 to reduce.
  4. Dreduction of the −OH-OH groups all the way to alkanes, removing every oxygen atom from the ring system entirely.

Question 506

[2 marks]organic chemistry / functional groups
Cholic acid's −OH-OH groups, shown in Fig.1, are secondary alcohols. Treating cholic acid with hot, acidified potassium dichromate(VI) mainly causes
  1. Aoxidation of the secondary −OH-OH groups to ketone (C=OC=O) groups on the ring system.
  2. Bno visible reaction, since all the −OH-OH groups in cholic acid are tertiary, not secondary.
  3. Creduction of the −COOH-COOH group to a primary alcohol.
  4. Dfurther oxidation of the −COOH-COOH group all the way to CO2CO_2 gas, releasing it from the molecule.

Question 507

[1 marks]organic chemistry / functional groups
Passing cholic acid vapour over hot Al2O3Al_2O_3 removes water from its −OH-OH groups by dehydration, forming a product containing a new

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Question 601

[1 marks]organic chemistry / amides
Phenylamine reacts with benzoic acid to form compound M. The type of reaction which occurs is
  1. Aoxidation
  2. Bcondensation
  3. Caddition
  4. Dhydrolysis

Question 602

[1 marks]organic chemistry / amides
The formula of compound M, formed from phenylamine and benzoic acid, is
  1. AC6H5CO2C6H5C_6H_5CO_2C_6H_5
  2. BC6H5NHC6H5C_6H_5NHC_6H_5
  3. CC6H5CH2NHC6H5C_6H_5CH_2NHC_6H_5
  4. DC6H5CONHC6H5C_6H_5CONHC_6H_5

Question 603

[1 marks]organic chemistry / amides
The functional group present in compound M is
  1. Aester
  2. Bamine
  3. Camide
  4. Dnitrile

The answers, and why they are the answers

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