Chemistry 9701/12 February/March 2019: question paper and mark scheme

Question

The Boltzmann distribution is shown for a sample of gas at an initial temperature, T1. T1 proportion of molecules with energy, E 0 0 molecular energy, E The sample of gas was heated to temperature, T2. What is the correct distribution for the higher temperature, T2? T2 proportion of molecules with A energy, E 0 0 molecular energy, E proportion of T2 molecules with B energy, E 0 0 molecular energy, E T2 proportion of molecules with C energy, E 0 0 molecular energy, E T2 proportion of molecules with D energy, E 0 0 molecular energy, E

Question

A 3.7 g sample of copper(II) carbonate is added to 25 cm3 of 2.0 mol dm–3 hydrochloric acid. Which volume of gas is produced under room conditions? A 0.60 dm3 B 0.72 dm3 C 1.20 dm3 D 2.40 dm3

Question

Which statement about a 3p orbital is correct? A It can hold a maximum of 6 electrons. B It has the highest energy of the orbitals with principal quantum number 3. C It is at a higher energy level than a 3s orbital but has the same shape. D It is occupied by one electron in an isolated phosphorus atom.

Question

The eight species that follow all have covalent bonds. In which pair do the species have different shapes from each other? A BeCl 2 and CO2 B CH4 and NH4+ C NH3 and BF3 D SCl 2 and H2O

Question

Histidine is an amino acid. histidine H H 2 H 1 H N O C H N C C C C 3 C N H H O H H What are the approximate bond angles 1, 2, and 3? 1 2 3 A 109.5 107 90 B 120 107 109.5 C 120 120 90 D 120 120 109.5

Question

A sample of gas occupies 240 cm3 at 37 °C and 100 kPa. How many moles of gas are present in the sample? A 9.32 × 10–6 B 9.32 × 10–3 C 0.0781 D 78.1

Question

P, Q and R represent three different structures of an element. P Q R Which structures are giant molecular? A P, Q and R B P and Q only C P and R only D Q and R only

Question

The standard enthalpy changes of combustion of carbon, hydrogen and methanol are shown. C(s) + O2(g) → CO2(g) = –394 kJ mol–1 H2(g) + 1 2 O2(g) → H2O(l) = –286 kJ mol–1 CH3OH(l) + 1 21 O2(g) → CO2(g) + 2H2O(l) = –726 kJ mol–1 Which expression gives the standard enthalpy change of formation of methanol in kJ mol–1? A –394 + (–286) – (–726) B –394 + (–286 × 2) – 726 C –394 + (–286 × 2) – (–726) D –726 – (–394) – (–286 × 2)

Question

The equation for a chemical reaction is shown. All substances are in their standard states. XeF6 + 3H2O → XeO3 + 6HF Which statement describes the standard enthalpy change of reaction for this reaction? A the enthalpy change when a total of one mole of products is produced B the enthalpy change when a total of one mole of reactants is reacted C the enthalpy change when one mole of water reacts D the enthalpy change when six moles of hydrogen fluoride are produced

Question

Acidified potassium manganate(VII) reacts with iron(II) ethanedioate, FeC2O4. The reactions taking place are shown. MnO4– + 8H+ + 5e– → Mn2+ + 4H2O Fe2+ → Fe3+ + e– C2O42– → 2CO2 + 2e– How many moles of iron(II) ethanedioate react with one mole of potassium manganate(VII)? A 0.60 B 1.67 C 2.50 D 5.00

Question

When copper is added to a solution of silver ions, the following equilibrium is established. Cu(s) + 2Ag+(aq) Cu2+(aq) + 2Ag(s) Kc = 1.0 × 105 What is the concentration of silver ions at equilibrium when [Cu2+] = 0.10 mol dm–3? A 5.0 × 10–7 mol dm–3 B 5.0 × 10–4 mol dm–3 C 1.0 × 10–3 mol dm–3 D 1.0 × 102 mol dm–3

Question

X, Y and Z are elements in Period 3 of the Periodic Table. The results of some experiments carried out with compounds of these elements are shown. result of adding result of adding result of adding element the oxide of the the chloride of the the oxide of the element to H2O(l) element to H2O(l) element to HCl (aq) X no reaction hydrolyses forms chloride salt Y forms hydroxide dissolves forms chloride salt Z forms acid hydrolyses hydrolyses Which statement could be correct? A X is Al and Y is Mg. B X is Si and Y is Na. C Y is Al and Z is P. D Y is Na and Z is Al .

Question

A solid Period 3 element, Q, is reacted with oxygen gas. Compound R is formed. When R is added to water the pH decreases. What could be the empirical formula of R? A Q2O4 B Q2O5 C Q4O10 D Q5O2

Question

Metal T reacts with water to produce a colourless solution. A white precipitate is produced when this colourless solution is mixed with aqueous sulfuric acid. What is metal T? A barium B magnesium C potassium D sodium

Question

When calcium nitrate thermally decomposes, oxygen is one of the products. Which volume of oxygen is produced under room conditions when 0.50 mol of calcium nitrate thermally decomposes? A 6.0 dm3 B 12.0 dm3 C 18.0 dm3 D 30.0 dm3

Question

L, M and N are Group 2 metals. L reacts more vigorously with dilute hydrochloric acid than N does. M(OH)2 is more soluble than N(OH)2. What could be the identities of L, M and N? L M N A Ba Ca Sr B Ba Sr Ca C Ca Ba Sr D Sr Ca Ba

Question

The table shows some reactions of a white compound, G. test observation silver nitrate is added to a solution of G a precipitate is formed which does followed by aqueous ammonia not dissolve when the ammonia is added solid G is warmed with a mixture of gases is formed concentrated sulfuric acid including hydrogen sulfide What could be the identity of G? A caesium chloride B lithium bromide C potassium sulfate D sodium iodide

Question

Under standard conditions, which statement is correct? A Cl 2(aq) can oxidise Br –(aq). B Cl 2(aq) can reduce Br –(aq). C Cl –(aq) can oxidise Br2(aq). D Cl –(aq) can reduce Br2(aq).

Question

Ammonia, NH3, and hydrazine, NH2NH2, are two compounds of nitrogen, N2. Which statement is correct? A The N–N bond in NH2NH2 is polar. B NH3 and NH2NH2 have lone pairs of electrons but N2 does not. C The oxidation number of each nitrogen in NH2NH2 is +2. D The reaction of nitrogen with hydrogen has a high activation energy.

Question

How many structural isomers are there of trichloropropane, C3H5Cl 3? A 3 B 4 C 5 D 6

Question

Compound L has the molecular formula C10H16. A sample of L reacted with an excess of hot, concentrated, acidified potassium manganate(VII). Compound M is produced. M O O OH O What could be the structure of compound L? A B C D

Question

Many reactions take place in the engine and catalytic converter of a car. Which pair of substances is produced both by the reactions in a car engine and in a catalytic converter? A carbon dioxide and unburnt hydrocarbons B carbon dioxide and water C carbon monoxide and nitrogen D carbon monoxide and unburnt hydrocarbons

Question

Structural isomerism and stereoisomerism should be considered when answering this question. 2-bromopentane is heated with an excess of ethanolic sodium hydroxide. How many different hydrocarbons are produced? A 1 B 2 C 3 D 4

Question

Bromopropane reacts with water as shown. CH3CH2CH2Br + H2O → CH3CH2CH2OH + HBr Which statement is correct? A This is an elimination reaction. B This is a hydrolysis reaction. C This is a redox reaction. D This reaction tends to proceed via the SN1 mechanism.

Question

Which product is formed when 3-methylpentane-1,3,4-triol is heated under reflux with an excess of acidified potassium dichromate(VI)? A HO2CCH2C(CH3)(OH)COCH3 B HO2CCH2COC(OH)(CH3)2 C OHCCH2C(CH3)(OH)COCH3 D HO2CCH2CO(CH3)COCH3

Question

Menthol is a naturally occurring alcohol. menthol OH When menthol is heated with concentrated sulfuric acid it reacts. The products formed include compound T. What could be the structure of compound T? A B C D O

Question

Structural isomerism only should be considered when answering this question. All the isomeric alcohols with the molecular formula C5H12O are added separately to warm alkaline aqueous iodine. How many of the isomers give a yellow precipitate? A 0 B 1 C 2 D 3

Question

When compound X is heated with Cr2O72– / H+, a colour change from orange to green is observed. Two tests are carried out on the organic product of this reaction. test result Tollens’ reagent no change 2,4-dinitrophenylhydrazine orange precipitate What could be compound X? A B C D O O OH OH H O 29 1 mole of each of the following four compounds is reacted separately with: ● an excess of sodium ● an excess of sodium carbonate. Which compound produces the same volume of gas with each of the two reagents? A B C D OH O O O OH OH H HO HO HO HO O

Question

In the question paper above.

Question

An infra-red spectrum shows a broad peak at 3000 cm–1 and a strong peak at 1710 cm–1. Which substance could have produced this spectrum? A methyl propanoate B propan-2-ol C propanoic acid D propanone Section B For each of the questions in this section, one or more of the three numbered statements 1 to 3 may be correct. Decide whether each of the statements is or is not correct (you may find it helpful to put a tick against the statements that you consider to be correct). The responses A to D should be selected on the basis of A B C D 1, 2 and 3 1 and 2 2 and 3 1 only are only are only are is correct correct correct correct No other combination of statements is used as a correct response. Use of the Data Booklet may be appropriate for some questions.

Question

In an experiment, 10 cm3 of an organic compound, J, in the gaseous state is reacted with an excess of oxygen. Steam, 20 cm3 of carbon dioxide and 5 cm3 of nitrogen are the only products. All gas volumes were measured at the same temperature and pressure. What could be the identity of J? 1 C2H6N2 2 C2H3N 3 C2H7N

Question

In which pairs do both species have the same number of unpaired electrons in p orbitals? 1 O and Cl + 2 F+ and Ga– 3 N and Kr3+

Question

In which reactions is the underlined element or compound reduced? 1 NaCl O + H2O2 → O2 + NaCl + H2O 2 2NH3 + 2Li → 2LiNH2 + H2 3 3CH3CH2OH + K2Cr2O7 + 4H2SO4 → 3CH3CHO + Cr2(SO4)3 + K2SO4 + 7H2O

Question

Some polluting gases are removed from car exhaust fumes using a catalytic converter. Platinum or palladium can be used as the catalyst. The reactions are faster when platinum is the catalyst than they are when palladium is the catalyst. Which statements are correct? 1 Platinum acts as a heterogeneous catalyst in these reactions. 2 The palladium-catalysed reactions have higher activation energies than the platinum-catalysed reactions. 3 The platinum-catalysed reactions are more exothermic than the palladium-catalysed reactions.

Question

Which statements about ceramics are correct? 1 Ceramics are good electrical conductors. 2 Ceramics are strong materials. 3 Ceramics have high melting points.

Question

Which types of bonding are present in ammonium carbonate, (NH4)2CO3? 1 ionic 2 covalent 3 co-ordinate (dative covalent)

Question

The diagram shows the structure of cholesterol. cholesterol CH3 CH3 CH3 HO Which statements about cholesterol are correct? 1 The molecule contains a secondary alcohol group. 2 The molecule contains two π bonds. 3 All carbon atoms in the four rings lie in the same plane. The responses A to D should be selected on the basis of A B C D 1, 2 and 3 1 and 2 2 and 3 1 only are only are only are is correct correct correct correct No other combination of statements is used as a correct response.

Question

Chlorine atoms in the upper atmosphere cause the breakdown of ozone. Cl + O3 → O2 + Cl O Cl O + O → Cl + O2 Which statements about these chlorine atoms are correct? 1 The chlorine atoms act as catalysts. 2 The chlorine atoms are free radicals. 3 The chlorine atoms are formed by heterolytic fission of a covalent bond in chlorofluorocarbons.

Question

The compounds listed are reacted with hydrogen cyanide. Which compounds produce a molecule containing a chiral centre? 1 butanal 2 butanone 3 pentan-2-one

Question

Carboxylic acids can be prepared from alcohols, nitriles or esters. Which statements are correct? 1 Both primary and secondary alcohols can be oxidised to carboxylic acids. 2 Carboxylic acids can be made from nitriles by hydrolysis. 3 Ethyl propanoate gives propanoic acid when reacted with hydrochloric acid.