ACJC_H2_CHEM_P1 Prelim

© ACJC 2014 9647/01/Prelim/14 [Turn over 2 Section A For each question there are four possible answers, A, B, C, and D. Choose the one you consider to be correct. 1 Wines often contain a small amount of sulfur dioxide that is added as a preservative. The sulfur dioxide content of a wine is found by the following method: A 50 cm 3 sample of white wine is reacted with 40.0 cm 3 of 0.01 mol dm -3 of excess aqueous iodine. The sulfur dioxide in the wine is oxidized to sulfate, SO 4 2-, in the process. The unreacted iodine requires exactly 23.60 cm 3 of 0.02 mol dm -3 sodium thiosulfate for complete reaction. What is the concentration of sulfur dioxide, in mol dm −3 , in the wine? A 1.64 x 10 −3 * B 3.28 x 10 −3 C 4.72 x 10 −3 D 9.44 x 10 −3 2 A sample of 0.16 g of liquid A is vaporised in a graduated syringe at 100 C and 1 atm. The final volume of the syringe that was recorded is 46 cm3. By assuming that 1 mol of vapour occupies 22.4 dm 3 at standard temperature and pressure, what is the relative molecular mass of A? A B C * D

© ACJC 2014 9647/01/Prelim/14 [Turn over 3 n- 3 Which one of the following sets of compounds consists of a giant ionic structure, a giant covalent structure and a simple covalent structure? A C6H5CO2H, P4O10 and BN B BaO2, ICl3 and SnCl2 * C AlCl3, AlF3 and SiC D SiO2, HCl and BeCl2 4 An ion IF4 n− has a square planar structure as shown below. What is the value of n? *A 1 B 2 C 3 D 4 5 Which of the following is a possible configuration of a stable M 3+ ion in the ground state? A 1s 2 2s 2 2p 3 B 1s 2 2s 2 2p 6 3s 2 3p 1 * C 1s 2 2s 2 2p 6 3s 2 3p 6 3d 2 D 1s 2 2s 2 2p 6 3s 2 3p 6 3d 2 4s 2 I F F F F n−

© ACJC 2014 9647/01/Prelim/14 [Turn over 4 6 S4N4 is a thermochomic solid which changes colour with temperature. S 4N4 has a cage structure as shown in the diagram. SS N N N N S S Given the following data, what is the average bond energy of S-N, in kJ mol-1? ∆Hf° (S4N4) = +460 kJ mol-1 ∆Hat° (sulfur) = +279 kJ mol-1 ∆Hat° (nitrogen) = +497 kJ mol-1 (S-S) bond energy in S4N4 = = +204 kJ mol-1 A 155 * B 280 C 395 D 559 7 Self-heating cans can offer benefits to campers without access to a stove or campfire. These soup cans have double walls with an ionic compound such as CaO in a packet and water between the walls. Upon opening the can, the packet breaks, the CaO reacts with water and warms up the soup. CaO (s) + H 2O (l)  Ca(OH)2 (s) What are the signs of ∆H, ∆S and ∆G for the overall process? ∆H ∆S ∆G *A - - - B - + - C + + - D + + +

© ACJC 2014 9647/01/Prelim/14 [Turn over 5 8 Acetals are derived from aldehydes or ketones, formed by reaction with two equivalents of an alcohol in the presence of an acid catalyst. The reaction below is an example of the formation of an acetal from propanone and methanol.