2015 HCI H1 Chemistry Prelims P1 Questions

CANDIDA NAME CHEMIS Paper 1 M Additional READ THE Write in so Complete There are possible a Choose th Each corr e Any rough HWA CH C2 Prelim Higher 1 ATE STRY Multiple Choi Materials: O D ESE INSTR oft pencil. the informa thirty ques nswers A, B e one you c ect answer w working sh ONG INST minary Exa ice Optical Mar Data Bookle RUCTIONS ation on the stions on th B, C and D. consider co will score o hould be do This d TITUTION amination rk Sheet (O et FIRST optical mar his paper. A . orrect and re ne mark. A ne in this bo document c ns MS) rk sheet (O Answer all q ecord your c mark will n ooklet. consists of 1 Write Write CT MS) as sho questions. F choice in so not be deduc 10 printed p e your name e your CT g GROUP own below. For each qu oft pencil o cted for a w pages. e roup 14S 18 Septem uestion, the on the OMS wrong answe Wri sha NR or F 8872/01 mber 2015 50 min ere are four S. er. ite and ade your IC FIN numbe r

2 SECTION A 1 A mixture of 10 cm3 of methane and 10 cm3 of ethane was sparked with an excess of oxygen. After cooling to room temperature, the residual gas was passed through aqueous potassium hydroxide. All gas volumes were measured at the same temperature and pressure. What volume of gas was absorbed by the alkali? A 15 cm 3 B 20 cm3 C 30 cm3 D 40 cm3 2 In which species are the numbers of protons, neutrons and electrons all different? 3 When iron reacts with aqueous iron(III) ions, iron(II) ions are formed as the only product. A final mixture, after the reaction has taken place, contains equal numbers of moles of Fe 2+(aq) and Fe3+(aq). Assuming the reaction has gone to completion, how many moles of Fe(s) and Fe3+(aq) were in the starting mixture? 4 The reaction pathway for a reversible reaction is shown below. Which statement is correct? A The activation energy of the reverse reaction is +80 kJ mol –1. B The enthalpy change for the forward reaction is +30 kJ mol–1. C The enthalpy change for the forward reaction is +50 kJ mol–1. D The enthalpy change for the reverse reaction is +30 kJ mol-1.

3 5 Sulfur dioxide gas is converted into sulfate ions when it is bubbled into a solution containing aqueous manganate(VII) ions. SO 2(g) + 2H2O(l) → SO4 2–(aq) + 4H+(aq) + 2e– MnO4 –(aq) + 8H+(aq) + 5e– → Mn2+(aq) + 4H2O(l) How will the pH of the reaction mixture change as sulfur dioxide is bubbled at constant rate into a well-stirred solution of manganate(VII) ions until its colour just fades? A a decrease B a decrease then an increase C an increase D an increase then a decrease 6 Enthalpy changes that are difficult to measure directly can often be determined using Hess’ Law to construct an enthalpy cycle. Which enthalpy change is indicated by X in the enthalpy cycle shown? A – 4 × the enthalpy of combustion of hydrogen B + 4 × the enthalpy of combustion of hydrogen C – 2 × the enthalpy of formation of water D + 2 × the enthalpy of formation of water 7 The table shows the physical properties of four substances. Which substance has a giant covalent structure?

4 8 Under the same conditions, which of the following ions would be deflected in a mass spectrometer to the same extent as C12 6 2+ ? A Li6 3 + B C12 6 + C N12 7 3+ D C13 6 2+ 9 Values for the ionic product of water, Kw, at two different temperatures are given below. temperature / oC Kw / mol2 dm-6 25 62 1.00 x 10-14 1.00 x 10-13 What can be deduced from this information? A Water is not neutral liquid at 62 oC B The ionic dissociation of water increases by a factor of 5 between 25 oC and 62 oC C The association of water molecules by hydrogen bonding increases as temperature rises. D The ionic dissociation of water is an endothermic process 10 Lead is the final product formed by a series of changes in which the rate-determining stage is the radioactive decay of uranium-238. This decay is a first-order reaction with half-life of 4.5 x 10 9 years. What would be the age of a rock sample originally lead-free, in which molar ratio of uranium to lead is 12.5% : 87.5% ? A 1.5 x 10 9 years B 4.5 x 109 years C 12.6 x 109 years D 13.5 x 109years 11 10 cm3 of a 0.01 mol dm-3 solution of nitric acid is diluted with 90 cm3 of water. What is the pH of the resulting solution? A 1 B 2 C 3 D 4

5 12 The magnitude of enthalpy change of neutralisation of aqueous sodium hydroxide by hydrochloric acid is 57.2 kJ mol -1, but the magnitude of enthalpy change of neutralisation of aqueous sodium hydroxide by aqueous ethanoic acid is 55.2 kJ mol-1. Which statement best explains the numerical difference in these values? A The process CH 3CO2H (aq) → CH3CO2 - (aq) + H+ (aq) is exothermic B The process CH3CO2H (aq) → CH3CO2 - (aq) + H+ (aq) is endothermic C Aqueous ethanoic acid is a weak acid and has fewer hydrogen ions than hydrochloric acid of the same concentration. D A smaller volume of aqueous hydrochloric acid is required for the neutralisation compared to that of ethanoic acid of the same concentration. 13 The equilibrium constant for the following reaction is very much less than 1. HPO 4 2(aq) + H2BO3 (aq) H2PO4 (aq) + HBO3 2(aq) Which one of one the following gives the correct relative strengths of the acids and bases in the reaction? acids bases A H2PO4  > H2BO3  and HBO3 2 > HPO4 2 B H2BO3  > H2PO4  and HBO3 2 > HPO4 2 C H2PO4  > H2BO3  and HPO4 2 > HBO3 2 D H2BO3  > H2PO4  and HPO 4 2- > HBO3 2 14 The rate of the reaction 3X(g) + Y(g) → Z(g) is given by the rate equation, rate = k [X]2[Y]. Two experiments using the same initial amounts of X and Y were carried out at temperature, T. The data is shown below. experiment volume of reaction vessel initial rate of reaction 1 V R 1 2 2 V R2 Which one of the following shows the relationship between R1 and R2? A R2 = 8 1 R1 B R2 = 4 1 R1 C R2 = R1 D R2 = 8R1

6 15 Use of the Data Booklet is relevant to this question. A chemist took 2.00 dm 3 of nitrogen gas, measured under room conditions, and reacted it with a large volume of hydrogen gas, in order to produce ammonia. Only 15.0% of the nitrogen gas reacted to produce ammonia. What mass of ammonia was formed? A 0.213 g B 0.425 g C 1.42 g D 2.83 g 16 Element Z is in period 3 of the Periodic Table. The following four statements describe the properties of element Z or its compounds. Three statements are correct descriptions. One of the statements is not correct because it does not fit with the other three. Which statement is not correct? A Element Z is a solid at room temperature which conducts electricity. B Element Z forms a chloride, ZCl 3, which reacts with more chlorine to give ZCl5. C The chloride ZCl3 reacts with water to give an acidic solution. D Adding NaOH(aq) to the solution resulting from the reaction of ZCl3 with water produces a white precipitate which is soluble in an excess of NaOH(aq). 17 Element G is found in Period 3 of the Periodic Table. The oxide and chloride of element G are separately mixed with water. The two resulting solutions have the same effect on litmus paper. What is the identity of element G? A aluminium C phosphorus B magnesium D sodium 18 Which one of the following pairs of compounds does the first member have a higher boiling point than the second member? A butane, 2–methylpropane B ethanol, water C trans but–2–ene, cis but–2–ene D 2–hydroxybenzoic acid, 4–hydroxybenzoic acid

7 19 Which molecular structure will have the smallest overall dipole? 20 Compound X has the molecular formula C4H10O2. X has an unbranched carbon chain and contai