2022 RSS Chem Prelims P2 SectA

1 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over NAME: NO: CLASS: RIVERSIDE SECONDARY SCHOOL PRELIMINARY EXAMINATION 2022 SUBJECT : Chemistry CODE/PAPER : 6092/02 LEVEL/STREAM : 4 Express DURATION : 1 hour 45 minutes READ THESE INSTRUCTIONS FIRST Write your name, index number and class in the spaces provided in the question paper. Write in dark blue or black pen. You may use an HB pencil for any diagrams or graphs. Do not use staples, paper clips, glue or correction fluid. Section A Answer all questions in the spaces provided. Section B Answer all three questions, the last question is in the form either/or. Answer all questions in the spaces provided. The number of marks is given in brackets [ ] at the end of each question or part question. A copy of the Periodic Table is printed on page 23. The use of an approved scientific calculator is expected, where appropriate. ________________________________________________________________________ This document consists of 23 printed pages.

2 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over Section A Answer all questions in this section in the spaces provided. The total mark for this section is 50. A1 (a) Choose from the following list of aqueous ions to answer the questions below. ammonium carbonate copper(II) hydrogen hydroxide iodide iron(II) nitrate Choose one ion from the list above which (i) is responsible for alkaline properties in a solution, ……………………………………………………………………….……………….…….…….[1] (ii) forms a green precipitate when added to aqueous sodium hydroxide, ………………………………………………………………………….……………………..….[1] (iii) forms a gas when added to acids, …………………………………………………………………………….…………………..….[1] (iv) forms a gas when added to alkalis, ………………………………………………………………………….………………..……….[1] (v) forms a reddish-brown deposit when magnesium is added. …………………………………………………………………………….………………..…….[1]

3 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over (b) Which statements about the separation of mixtures are true and which are false? Put a tick (🗸) in one box in each row. true false The separation of mixtures is a chemical process. Simple distillation allows the recovery of ethanol from water. In chromatography, the same substance has different Rf values in different solvents. [2] [Total: 7]

4 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over A2 Fig. 2.1 shows the structure of an atom. The electrons are missing. Fig. 2.1 (a) Complete Table 2.2 about the three particles found in this atom. Table 2.2 particle name of particle relative mass of the particle relative charge of the particle 1 1 1+ × electron 1- [2] (b) Complete the diagram in Fig. 2.1 to show the arrangement of the electrons in the atom. [1] (c) In the manufacture of the body of aircrafts, a small amount of the atom is added to aluminium to make it stronger. With the help of a labelled diagram, explain how the addition of a small amount of the atom increases the strength of the body of aircrafts. ……………………………………………………………………………………………….…….……… ……………………………………………………………………………………………….……….…… ………………………………………………………………………………………………………..…[3] [Total: 6]

5 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over A3 This question is about the halogens. (a) Table 3.1 s hows data about the densit ies and melting points of three halogens, chlorine, bromine and iodine. Complete the table by filling in the name of each halogen. Table 3.1 name of halogen density (g/ cm3) melting point (oC) 3.21 ‒7.3 4.94 114 0.00312 ‒102 [1] (b) Seawater contains sodium bromide. (i) Bromine can be produced from seawater by displacement. Name an element that can displace bromine and give a reason for your choice. name: ……………………………………………………..…………………….…………….….. reason: …………………………………………………………………………………..….....[2] (ii) Describe a simple test, other than displacement, that can be used to show that sea water also contains iodide ions. test: ……………….……………………………………………………………….………….….. result: ……………..…………………...…………………………………………………….....[2] [Total: 5]

6 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over A4 Fig. 4.1 shows a can of soup in a self-heating device. Piercing an internal water sachet with a special tool causes the solid anhydrous calcium chloride to mix with the water. Fig. 4.1 (a) The temperature of the soup rises by 60 °C within 10 minutes. Name the type of reaction that occurred when anhydrous calcium chloride mixes with water. ……………………………………………………………………………………..…………………....[1] (b) Table 4.2 shows the changes in heat energy for the reaction involving some substances with water. Table 4.2 substances ∆H (kJ/ mol) ammonium nitrate +25 concentrated sulfuric acid ‒71 lithium chloride ‒37 Discuss why lithium chloride is the most suitable replacement for calcium chloride to warm the soup. …………………………………………………………………………………….………………………. …………………………………………………………………………………….………………………. …………………………………………………………………………………….………………………. …………………………………………………………………………………….………………….…[3] pierce pierce water tin calcium chloride

7 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over (c) When the can is pierced, aqueous calcium chloride forms. CaCl2(s) → CaCl2(aq) Complete the energy profile diagram below. Your diagram should include: • the reactants and products, • labels to show the enthalpy change and the activation energy. [Total: 7] energy (kJ/ mol) progress of reaction [3]

8 Riverside Secondary School 6092/02/4E/PRELIM/2022 [Turn over A5 Hydrogen peroxide is a colourless liquid. An aqueous solution of hydrogen peroxide reacts with the iodide ions in acidified potassium iodide to form water and iodine according to the equation shown below. H2O2(aq) + 2H+(aq) + 2I‒(aq) → 2H2O(l) + I2(aq) (a) (i) Complete Table 5.1 to show the oxidation states of oxygen and iodine before and after the reaction. Table 5.1 element oxidation state before the reaction oxidation state after the reaction oxygen iodine [2] (ii) Use the information in Table 5.1 to explain why this is a redox reaction. …………………………………………………………………………………….………………... …………………………………………………………………………………….……………...[1] (iii) Describe the colour change for the above reaction. ……………………………………………………………………………………….…………...[1]

9 Riverside Secondary School