Chemistry 9701/12 October/November 2019: question paper and mark scheme

Question

The diagram shows a Boltzmann distribution of the energies of gaseous molecules and the activation energies, Ea, of a reaction with and without a catalyst. proportion of molecules with energy, E 0 0 Ea1 Ea2 molecular energy, E Which statement about this distribution curve is correct? A If the temperature of the gas is increased, the maximum of the curve becomes higher. B If the temperature of the gas is increased, the maximum of the curve moves to the left. C The fraction of molecules that react in the presence of a catalyst is shown by . D The fraction of molecules that react in the absence of a catalyst is shown by .

Question

In this question it should be assumed that (NH4)2CO3.H2O(s) dissolves in water without causing an increase in volume. Which mass of (NH4)2CO3.H2O(s) should be added to 800 cm3 of water to form a 0.100 mol dm–3 solution of NH4+ ions? A 4.56 g B 7.13 g C 9.12 g D 14.3 g

Question

The graph shows the successive ionisation energies of element X and element Y. Both elements are in Period 3. key element X element Y energy 0 1 2 3 4 5 6 7 8 9 10 successive ionisation energies Which statement is correct? A An atom of element X needs one extra electron for a full outer shell; an atom of element Y needs three extra electrons for a full outer shell. B An atom of element Y has five electrons in the 3p subshell. C Element X has an oxidation number of +7 in most of its compounds. D When element X combines with element Y, the bonding is ionic.

Question

Which statement about the electrons in a ground state carbon atom is correct? A Electrons are present in four different energy levels. B There are more electrons in p orbitals than there are in s orbitals. C The occupied orbital of highest energy is spherical. D The occupied orbital of lowest energy is spherical.

Question

In this question you should assume the vapour behaves as an ideal gas. 0.175 g of a volatile liquid produces a vapour of volume 4.50 × 10–5 m3 at 100 °C and pressure of 1.013 × 105 Pa. What is the Mr of the liquid? A 31.9 B 87.1 C 119 D 127

Question

Which reaction is endothermic? A Ca(OH)2(aq) + 2HCl (aq) → CaCl 2(aq) + 2H2O(l) B 2Cl (g) → Cl 2(g) C 2Ca(s) + O2(g) → 2CaO(s) D CaCO3(s) → CaO(s) + CO2(g)

Question

Which equation correctly represents the standard enthalpy change of atomisation of the given element? A 1 I (g) 2 2 → I(g) B Na(s) → Na(g) C Cl 2(g) → 2Cl (g) D Na(g) → Na+(g) + e–

Question

(NH4)2Cr2O7 decomposes when heated. (NH4)2Cr2O7 → N2 + 4H2O + Cr2O3 Which element is oxidised and which element is reduced? oxidised reduced A chromium nitrogen B hydrogen chromium C nitrogen chromium D nitrogen hydrogen

Question

When lead(II) sulfide, PbS, is heated in air, sulfur dioxide and lead(II) oxide are formed. What is the equation for the reaction between PbS and oxygen? A PbS + 2O2 → SO2 + PbO2 B PbS + 2 21 O2 → SO3 + PbO2 C PbS + 1 21 O2 → SO2 + PbO D PbS + 2O2 → SO3 + PbO

Question

The decomposition of SO3(g) is a dynamic equilibrium. 2SO3(g) 2SO2(g) + O2(g) What happens when the pressure of the system is increased? A The rate of reaction will decrease and the position of the equilibrium will move to the left. B The rate of reaction will decrease and the position of the equilibrium will move to the right. C The rate of reaction will increase and the position of the equilibrium will move to the left. D The rate of reaction will increase and the position of the equilibrium will move to the right.

Question

Hydrated aluminium ions undergo the following reaction. [Al (H2O)6]3+(aq) + H2O(l) [Al (H2O)5OH]2+(aq) + H3O+(aq) Which statement about this reaction is correct? A H2O(l) and [Al (H2O)5OH]2+(aq) are a conjugate acid-base pair. B H2O(l) is acting as an acid as it is donating H+ ions. C If OH–(aq) is added, the equilibrium will move to the right. D Kc varies as the pH is varied.

Question

Which diagram correctly shows the electronegativity of the elements Na, Mg, Al and Si plotted against their first ionisation energies? A B Si Si Al Al electronegativity electronegativity Mg Mg Na Na first ionisation energy first ionisation energy C D Na Na Al Mg electronegativity electronegativity Mg Al Si Si first ionisation energy first ionisation energy

Question

Which statement about the compounds of Group 2 elements magnesium to barium is correct? A Carbonates of Group 2 elements produce bubbles when added to dilute nitric acid. B Nitrates of Group 2 elements produce nitrogen and oxygen on heating. C Oxides of Group 2 elements produce bubbles when added to dilute hydrochloric acid. D The oxides of Group 2 elements are amphoteric.

Question

When equal volumes of saturated solutions of barium hydroxide and calcium hydroxide are mixed, a white precipitate, Y, forms. The mixture is filtered and carbon dioxide is bubbled through the filtrate, producing a second white precipitate, Z. What are Y and Z? Y Z A Ba(OH)2 Ca(OH)2 B Ba(OH)2 CaCO3 C Ca(OH)2 BaCO3 D Ca(OH)2 Ba(OH)2

Question

Chlorate(V) ions, Cl O3–, are produced in the redox reaction between chlorine and hot aqueous sodium hydroxide. Oxidation numbers can be used to help balance the equation for this reaction. vCl 2(g) + wOH–(aq) → xCl –(aq) + yCl O3–(aq) + zH2O(l) What are the values of v, x and y in the balanced equation? v x y A 2 3 1 B 3 4 2 C 3 5 1 D 7 12 2

Question

The properties of chlorine, bromine and their compounds are compared. Which property is smaller for chlorine than for bromine? A bond strength of the hydrogen-halide bond B first ionisation energy C solubility of the silver halide in NH3(aq) D strength of the van der Waals’ forces between molecules of the element

Question

Solid sodium iodide reacts with concentrated sulfuric acid to form more than one product that contains sulfur. What is the lowest oxidation number of sulfur in these products? A –2 B 0 C +4 D +6

Question

Which emission from an internal combustion engine contributes to the erosion of marble statues? A carbon monoxide B nitrogen C nitrogen dioxide D unburnt hydrocarbons

Question

Ammonia, carbon dioxide and water react together to form ammonium carbonate. Which statement about this reaction is correct? A It is a redox reaction. B It is an acid-base reaction. C The H–N–H bond angle decreases as a consequence of this reaction. D The three substances react in a 1 : 1 : 1 ratio in this reaction.

Question

Structural isomerism and stereoisomerism should be considered when answering this question. How many isomers with the formula C5H10 have structures that involve π bonding? A 3 B 4 C 5 D 6

Question

The diagram shows the skeletal formula of phenazine. N N phenazine What is the empirical formula of phenazine? A C6H4N B C6H6N C C12H8N2 D C12H12N2

Question

An organic compound X reacts with hot, concentrated acidified potassium manganate(VII) solution to give a single carbon-containing product. What could be X? A CH2C(CH3)2 B CH3CHCHCH3 C CH2CHCH2CH3 D CH3CH2CH2CH3 23 1-chloro-2-methylbutane reacts with sodium cyanide in ethanol in a nucleophilic substitution reaction. What is the most likely intermediate or transition state in this reaction? A B – – H H H 3C CH2CH3 NC C Cl NC C Cl CH(CH3)CH2CH3 CH3 C D H 3C CH2CH3 H H +C +C CH3 CH(CH3)CH2CH3

Question

In the question paper above.

Question

Propan-1-ol can be reacted with acidified potassium dichromate(VI) to form propanoic acid, reaction 1, or propanal, reaction 2. O O reaction 1 reaction 2 CH3CH2COH CH3CH2CH2OH CH3CH2CH propan-1-ol How can the reaction be carried out to ensure that reaction 2 occurs rather than reaction 1? A An excess of acidified potassium dichromate(VI) is used. B An excess of concentrated sulfuric acid is added. C The reaction mixture is distilled immediately after mixing. D The reaction mixture is heated under reflux.

Question

What is the smallest amount of oxygen molecules needed for the complete combustion of 40.0 g of methanol? A 1.88 moles B 2.50 moles C 3.75 moles D 5.00 moles

Question

Compound X has stereoisomers and forms a precipitate when warmed with Fehling’s reagent. What could be the structure of compound X? A B C D O O O O

Question

The diagram shows the structure of Y. H H H H C C C C C H H O H O H Two suggestions are made about Y. 1 Y can be oxidised by hot, acidified dichromate(VI) ions. 2 One mole of Y gives one mole of tri-iodomethane when it reacts with an excess of alkaline aqueous iodine. Which suggestions are correct? A both 1 and 2 B 1 only C 2 only D neither 1 nor 2

Question

Esters can be prepared by the reaction of a carboxylic acid with an alcohol in the presence of concentrated sulfuric acid. Which row gives the correct names of the reagents that would be suitable to prepare ester Z? Z O O alcohol carboxylic acid A butan-1-ol methyl propanoic acid B propan-1-ol butanoic acid C propan-2-ol butanoic acid D propan-2-ol propanoic acid

Question

Compound Q can be hydrolysed by HCl (aq). The two products of this hydrolysis have the same empirical formula. What could Q be? A CH3CO2CH2CH2OH B CH3CO2CH2CH2CO2H C CH3CH2CO2CH2CH2CH3 D CH3CH2CH(OH)CH(OH)CH2CH3

Question

Substance T was analysed and found to contain 62.07% carbon, 10.34% hydrogen and 27.59% oxygen. The infra-red spectrum of substance T is shown. 100 transmittance /% 50 0 4000 3000 2000 1500 1000 500 wavenumber / cm–1 Which substance could be T? A B C D HO O O HO OH OH OH 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

Which gaseous molecules are polar? 1 ammonia 2 hydrogen sulfide 3 boron trifluoride

Question

A carbon monoxide molecule, CO, has three bonds between the carbon atom and the oxygen atom. Which features are present in one CO molecule? 1 two lone pairs of electrons 2 a co-ordinate (dative covalent) bond from oxygen to carbon 3 two π bonds

Question

Carbon can exist as allotropes which include graphite, diamond and a fullerene. Which statements are correct? 1 All three allotropes contain covalent bonds. 2 All three allotropes are giant molecular. 3 All three allotropes have delocalised electrons. 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

The reaction pathway diagram for a reversible reaction is shown. 50 energy / kJ mol–1 20 progress of reaction Which statements are correct? 1 The enthalpy change for the backward reaction is –20 kJ mol–1. 2 The forward reaction is endothermic. 3 The activation energy for the forward reaction is +70 kJ mol–1.

Question

Silicon forms a tetrachloride, SiCl 4. Which statements are correct? 1 In SiCl 4, the Si is δ+ and each Cl is δ–. 2 SiCl 4 is a liquid at room temperature. 3 SiCl 4 reacts with water to give an acidic solution and a precipitate.

Question

Which statements about ammonia are correct? 1 An ammonia molecule has three bond pairs and one lone pair of electrons. 2 When ammonia is bubbled into water the pH of the solution increases. 3 Ammonia gas can be made by warming ammonium sulfate with aqueous hydrochloric acid.

Question

Following fractional distillation of crude oil, which processes can be used to produce propene from larger hydrocarbon molecules? 1 cracking 2 reduction 3 polymerisation

Question

Bromoethane undergoes nucleophilic substitution reactions. Which statements are correct? 1 Bromoethane reacts with aqueous NaOH to make ethanol. 2 Bromoethane reacts with ethanolic NH3 to make ethylamine. 3 Bromoethane reacts with ethanolic KCN to make ethanenitrile.

Question

Which reagents, when used in excess, can convert Y into Z? CH3CH(OH)CO2H → CH3CH(OH)CO2Na Y Z 1 Na 2 Na2CO3 3 NaOH

Question

Each of the compounds below is treated separately with an excess of NaBH4. The product of each reaction is then heated with an excess of concentrated H2SO4. Which compounds give only one final product with the molecular formula C7H10? 1 2 3 O O O O H O H O H