Chemistry 9701/11 May/June 2020: question paper and mark scheme

Question

Ethene can be oxidised to form epoxyethane, C2H4O. C2H4(g) + 1 O (g) 2 2 C2H4O(g) ∆H o = –107 kJ mol–1 Which set of conditions gives the greatest yield of epoxyethane at equilibrium? temperature pressure / °C A high 100 B high 200 C low 100 D low 200

Question

Cobalt can form the positive ion Co(NH3)4Cl 2+. What is the oxidation number of cobalt in this ion? A +1 B +2 C +3 D +6

Question

When considering one molecule of ethene, which row describes both the hybridisation of the atomic orbitals in the carbon atoms and the overall bonding? hybridisation bonding A sp2 4 σ bonds 1 π bond B sp2 5 σ bonds 1 π bond C sp3 4 σ bonds 1 π bond D sp3 5 σ bonds 1 π bond

Question

10 cm3 of ethane is burned in 45 cm3 of oxygen at a pressure of 101 kPa and a temperature of 200 °C. Complete combustion takes place. What is the total volume of gas present when the reaction is complete, measured under the same conditions? A 30 cm3 B 50 cm3 C 55 cm3 D 60 cm3

Question

Two reactions are shown. H2(g) → 2H(g) CO(g) + 1 O (g) 2 2 → CO2(g) If molar amounts are used, how can the two energy changes associated with these reactions be described? A enthalpy of atomisation and enthalpy of combustion B enthalpy of atomisation and enthalpy of formation C bond energy and enthalpy of combustion D bond energy and enthalpy of formation

Question

The diagram shows the Boltzmann energy distribution curves for molecules of a sample of a gas at two different temperatures. Which letter on the axes represents the most probable energy for molecules of the same sample of gas at the lower temperature? A B C D

Question

What are the units of Kp for the reaction shown? H2O(g) + C(s) H2(g) + CO(g) A Pa–1 B Pa C Pa2 D no units

Question

In this question you should use changes in oxidation numbers to balance a chemical equation. Acidified potassium dichromate(VI) solution can oxidise a solution of V2+ ions. The equation for this reaction is shown. a Cr2O72– + b V2+ + c H+ → d Cr3+ + e VO3– + f H2O What is the ratio a : b in the correctly balanced equation? A 1:1 B 1:2 C 2:1 D 4:1

Question

A sample of argon gas has a mass of 0.20 g, at a pressure of 100 000 Pa and a temperature of 12 °C. Which volume does the gas occupy? A 1.2 × 10–4 cm3 B 5.0 cm3 C 59 cm3 D 119 cm3

Question

In which pair does each species have the same number of unpaired electrons? A Al and Cu2+ B Ca and Cr3+ C Ca and Ni2+ D Fe3+ and O2–

Question

A sample of solid ammonium chloride decomposes on heating. solid ammonium chloride → ammonia gas + hydrogen chloride gas A total of 2.4 × 1021 molecules of gas is formed. How many hydrogen atoms are present in the gaseous products? A 1.2 × 1021 B 2.4 × 1021 C 4.8 × 1021 D 9.6 × 1021

Question

A white powder is a mixture of sodium chloride and sodium iodide. It is dissolved in water in a test-tube. An excess of aqueous silver nitrate is added to the test-tube. A precipitate, X, is observed. An excess of concentrated ammonia is then added to the test-tube containing X. After the test-tube has been shaken, a precipitate, Y, is observed. Which statement about X or Y is correct? A X is a pure white colour. B X is pure silver iodide. C Y is pure silver chloride. D Y is yellow. 13 6.90 g of an ammonium salt is heated with an excess of aqueous sodium hydroxide. The volume of ammonia produced, measured under room conditions, is 2.51 dm3. Which ammonium salt is used? A ammonium carbonate (Mr = 96.0) B ammonium chloride (Mr = 53.5) C ammonium nitrate (Mr = 80.0) D ammonium sulfate (Mr = 132.1)

Question

In the question paper above.

Question

An excess of MgO is shaken with water. The resulting mixture is filtered into test-tube P. An excess of BaO is shaken with water. The resulting mixture is filtered into test-tube Q. Which oxide reacts more readily with water and which filtrate has the lower pH? oxide reacts more test-tube with readily with water filtrate of lower pH A BaO P B BaO Q C MgO P D MgO Q

Question

Element Z has a giant structure. The chloride of Z reacts with water to give a solution with a pH less than 5. Which pair shows two elements which could be Z? A aluminium, magnesium B aluminium, silicon C phosphorus, magnesium D phosphorus, silicon

Question

Sodium, aluminium and silicon are three elements in Period 3. Each element forms an oxide. Which row has three correct properties of these oxides? sodium oxide aluminium oxide silicon dioxide A basic basic amphoteric B giant ionic giant ionic simple molecular C high melting point low melting point high melting point D reacts with water no reaction with water no reaction with water 17 0.25 g of anhydrous magnesium nitrate is heated strongly until it completely decomposes. What is the total volume of gas produced, measured under room conditions? A 40 cm3 B 81 cm3 C 101 cm3 D 202 cm3

Question

In the question paper above.

Question

Astatine, At, is below iodine in Group 17 of the Periodic Table. Which statement is most likely to be correct? A AgAt(s) reacts with an excess of dilute aqueous ammonia to form a solution of a soluble complex. B Astatine and KCl (aq) react to form KAt(aq) and chlorine. C KAt(aq) and dilute sulfuric acid react to form HAt(g). D NaAt(s) and concentrated sulfuric acid react to form astatine.

Question

What is the order of increasing melting point of the three chlorides shown? CCl 4 MgCl 2 PCl 5 lowest highest melting point melting point A CCl 4 PCl 5 MgCl 2 B MgCl 2 CCl 4 PCl 5 C MgCl 2 PCl 5 CCl 4 D PCl 5 CCl 4 MgCl 2

Question

The skeletal formula of compound X is shown. O Which row is correct? observation on molecular addition of X to formula of X Fehling’s reagent A C7H14O no change B C7H14O red precipitate forms C C7H16O no change D C7H16O red precipitate forms

Question

Which statement is correct? A 2,2-dimethylpropanoic acid is an isomer of propyl methanoate. B 2-methylbutan-2-ol is an isomer of hexan-3-ol. C 3-methylbutan-2-one is an isomer of pentanal. D 3,3-dimethylbutan-2-one is an isomer of pentan-3-one.

Question

But-1-ene and but-2-ene are treated separately with cold, dilute acidified manganate(VII) ions. Four students, W, X, Y and Z, make statements about these alkenes and the diols formed from them. W One diol contains two primary alcohol groups. X One diol contains a primary and a secondary alcohol group. Y One diol contains two secondary alcohol groups. Z Both alkenes exhibit cis-trans isomerism. Which two students are correct? A W and Y B W and Z C X and Y D X and Z 23 2-bromo-2-methylpentane is a tertiary halogenoalkane. Which organic products are formed when 2-bromo-2-methylpentane reacts with a hot concentrated ethanolic solution of sodium hydroxide? A 2-methylpent-1-ene only B 2-methylpent-1-ene and 2-methylpent-2-ene C 2-methylpent-2-ene only D 2-methylpent-2-ene and 4-methylpent-2-ene

Question

In the question paper above.

Question

Poly(propene) is an addition polymer. What are the C–C–C bond angles along its polymer chain? A They are all 109°. B Half of them are 109° and half are 120°. C Half of them are 90° and half are 180°. D They are all 120°.

Question

An alcohol has the molecular formula C5H12O. It has several isomers. Which isomer forms a yellow precipitate with alkaline aqueous iodine? A 2,2-dimethylpropan-1-ol B 2-methylbutan-2-ol C 3-methylbutan-2-ol D pentan-3-ol

Question

When compound X is heated under reflux with aqueous sodium hydroxide solution two products are formed: sodium ethanoate and hexan-1-ol. What is compound X? A B C D O O O O O O O O

Question

What is the major product Z of the following reaction? an excess of dry HBr Z warm A B C D Br Br Br Br Br Br Br Br

Question

The structure of compound Q is shown. compound Q O O O O How many chiral centres are present in a molecule of Q? A 4 B 5 C 6 D 7

Question

Compound X has the infra-red spectrum shown. 100 transmittance / % 50 0 4000 3000 2000 1500 1000 500 wavenumber / cm–1 What could be the identity of compound X? A ethanoic acid B ethanol C ethylethanoate D propanone

Question

Which reaction produces an organic anion with a good yield? A heating ethanenitrile under reflux with dilute sodium hydroxide B heating ethanenitrile under reflux with dilute sulfuric acid C heating ethane with sodium metal D heating ethanol under reflux with dilute sodium hydroxide 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

The definitions of many chemical terms can be illustrated by chemical equations. Which terms can be illustrated by an equation that includes the formation of a positive ion? 1 first ionisation energy 2 heterolytic fission of a covalent bond 3 enthalpy change of atomisation

Question

Which molecules have no overall dipole moment? 1 boron trifluoride 2 methane 3 phosphorus pentafluoride

Question

Carbon exists in several different forms. Two of these forms are buckminsterfullerene and graphene. Buckminsterfullerene is a fullerene allotrope of carbon. Which statements about buckminsterfullerene and graphene are correct? 1 Both have delocalised electrons. 2 Buckminsterfullerene has a giant molecular structure. 3 The carbon atoms in graphene form a tetrahedral lattice. 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

Carbon monoxide burns readily in oxygen to form carbon dioxide. What does this information suggest? 1 The +4 oxidation state of carbon is more stable than the +2 state. 2 The standard enthalpy change of formation of carbon dioxide is more negative than the standard enthalpy change of formation of carbon monoxide. 3 The value of the equilibrium constant for the reaction, 2CO(g) + O2(g) 2CO2(g), is likely to be high.

Question

The catalytic converters fitted to cars remove pollutants from the exhaust gases. Some of the reactions that occur involve oxygen, which comes from the air. Which pollutants in the exhaust gases will react with oxygen on the surface of the catalytic converter? 1 NO2 2 unburnt fuel 3 CO

Question

Chlorine reacts with sodium hydroxide in two different ways depending upon the temperature. reaction 1 Cl 2 + 2OH– → Cl – + Cl O– + H2O reaction 2 3Cl 2 + 6OH– → 5Cl – + Cl O3– + 3H2O Which statements about these reactions are correct? 1 Reaction 2 requires a higher temperature than reaction 1. 2 The products of reaction 1 show chlorine in two different oxidation states. 3 The products of reaction 2 show oxygen in two different oxidation states.

Question

In which of the reactions is the organic compound oxidised by the given reagent? 1 CH3CHO + HCN reagent 2 CH3CH2CH2CHO + Tollens’ reagent 3 CH3CH2CHO + Fehling’s reagent

Question

When the apparatus is set up as shown, an orange precipitate forms in test-tube Z. Y Z air compound Q + acidified potassium 2,4-dinitrophenylhydrazine dichromate(VI) reagent warm What could compound Q be? 1 CH3CH2CH2OH 2 CH3CH(OH)CH3 3 (CH3)3COH

Question

Chlorofluoroalkanes that diffuse into the stratosphere are broken down by ultraviolet radiation. Radicals are generated that cause depletion of ozone. What are these radicals? 1 chlorine radicals 2 fluorine radicals 3 alkyl radicals 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

A mixture of the three isomers of C2H2Cl 2 is polymerised. Which sequences will be seen within the polymer chains? 1 2 3 Cl H H H Cl H C C C C C C Cl Cl Cl Cl H H