2022 Punggol Sec Chemistry P3

EXP PUNGGOL SECONDARY SCHOOL SECONDARY 4/5 EXPRESS 2022 PRELIMINARY EXAMINATION QUESTION & ANSWER BOOKLET NAME CLASS INDEX NUMBER Science Chemistry Paper 3 5076/03 26 August 2022 1 hour 15 minutes READ THESE INSTRUCTIONS FIRST Write your class, register number and name on all the work you hand in. You may use a HB pencil for any diagrams, graphs, tables or rough working. Write in dark blue or black ink. Do not use staples, paper clips, glue or correction fluid. The use of an approved scientific calculator is expected, where appropriate. You may lose marks if you do not show your working or if you do not use appropriate units. Section A (45 marks) Answer all questions. Write your answers in the spaces provided on the question paper. Section B (20 marks) Answer any two questions. Write your answers in the spaces provided on the question paper. A copy of the Periodic Table is printed on page 14. The number of marks is given in brackets [ ] at the end of each question or part question. For Examiner’s use Parent’s Signature Section A /45 Section B /20 - - Total /65 This paper consists of 14 printed pages and 0 blank page.

2 Section A Answer all the questions in the spaces provided. 1 The diagrams show the atoms in four substances, W, X, Y and Z. W X Y Z (a) Which of the above diagram represents (i) copper wire : …………………… (ii) stainless steel wire : …………………… [2] (b) Explain why stainless steel wire is more difficult to bend than a copper wire. …………………………………………………………………………………………....… ………………………………………………………………………………………….…... ……………………………………………………………………………………………… …………………………………………………………………………………………….[2] [Total:4] 2 Iron (III) chloride, FeCl3, is formed when iron, Fe, is heated in chlorine gas. (a) Write a balanced chemical equation for this reaction. ……………………………………………………………………………………………[2] (b) State with reasons, whether iron is being oxidised or reduced or neither of these. …………………………………………………………………………………………….. …………………………………………………………………………………………….. ……………………………………………………………………………………………[2] [Total:4]

3 3 Separating atmospheric air into its constituent gases is an important process for obtaining nitrogen and oxygen. (a) (i) State the process used to separate air to obtain nitrogen and oxygen. ……………………………………………………………………………….....….[1] (ii) Describe why this process is able to separate the two gases. ………………………………………………………………………………………. …………………………………………………………………………..………….[1] (b) Describe the observation when a glowing splint is placed into a gas jar filled with oxygen. ………………………………………………………………………………………........[1] (c) Draw a ‘dot and cross’ diagram to show the bonding in a molecule of oxygen. Show only the outer shell electrons. [2] [Total:5] 4 Table 4.1 describes three different oxides. Complete the table. Table 4.1 oxides formula of oxide nature of oxide (acidic /basic /amphoteric) solubility in water sulfur SO2 acidic magnesium MgO zinc No [Total:5]

4 5 Table 5.1 contains details of seven different atoms. The letters do not represent chemical symbols of elements. Table 5.1 S T V W X nucleon number 3 19 14 19 40 proton number 2 9 7 10 20 electronic configuration 2 2.7 2.5 2.8 2.8.8.2 Use Table 5.1 to state which atom(s) S, T, V, W, and X. (a) has only one neutron ………… (b) can form positive ions ……….... (c) forms covalent compounds that are diatomic ………… and …………. (d) are noble gases ………… and …………. [6] [Total:6] 6 Table 6.1 shows some properties of lithium and other Group I elements. Table 6.1 metal density g/cm3 melting point /°C boiling point /°C lithium 0.53 181 1342 sodium 0.97 98 883 potassium 0.86 63 759 rubidium 1.53 39 686 Use the information in Table 6.1 to answer the following when relevant. (a) (i) Write the balanced equation for the reaction of lithium with water. ………………………………………………………………………………………..[2] (ii) Explain why Group I elements are also known as alkali metals. ……………………………………………………………………………………..….... …………………………………………………………………………………….….[1]

5 (b) (i) Explain why rubidium is a liquid at a temperature of 40 °C. ………………………………………………………………………………...……..[1] (ii) Explain why a piece of rubidium strip will not float on a beaker of water. ……………………………………………………………………………………….[1] (c) Describe two observations when sodium reacts with water. ………………………………………………………………………………………..… …………………………………………………………………………………………. ……………………………………………………………………………………….[2] [Total:7] 7 A homologous series is a group of compounds that have similar chemical properties and the same general formula. Complete Table 7.1. Show all the bonds in the structures. Table 7.1 homologous series name of compound structures alkanes alkenes propene propanol [4] [Total:4] C H H H H

6 [Total:5] 8 Fig 8.1 describes some properties of compound A. Fig 8.1 Suggest the identity of substances A, B, C, D and E. A: ……………………………….. B: ……………………………….. C: ……………………………….. D: ……………………………….. E: ……………………………….. [5] compound A add aluminium foil and warm with aqueous sodium hydroxide add aqueous sodium hydroxide white precipitate D that dissolves in excess gas B that gives white precipitate with limewater add dilute nitric acid pungent gas E that turns damp red litmus paper blue colourless solution C white precipitate that dissolves in excess add aqueous ammonia

7 9 Table 9.1 shows some information about the compounds in a homologous series. Table 9.1 compound molecular formula relative molecular mass, Mr boiling points / °C methanol CH3OH 32 65 ethanol C2H5OH 46 78 propanol C3H7OH 60 97 butanol C4H9OH 74 117 (a) What is a homologous series? ………………………………………………………………………..………………..…… ………………………………………………………………………………….….……….. ……………………………………………………………………...........….............….[2] (b) Describe the change in the flammability from methanol to propanol. ………………………………………………………………………..……………..…...[1] (c) (i) Calculate the relative molecular mass of pentanol, which has five carbon atoms in a molecule. [1] (ii) Predict the boiling point of pentanol. …………………………………………………………………………...…..…..…[1] [Total:5]

8 Section B Answer any two questions from this section in the spaces provided. 10 A student investigates how the speed of a reaction changes over time. 100 ml of 1 mol/dm3 dilute hydrochloric acid, HCl, is added into a conical flask. Excess powdered sodium carbonate is added to the acid in the flask. A gas syringe is immediately attached to the conical flask with suitable connectors and the volume of gas produced over time was measured with a stop watch regularly. The measurement was stopped after 10 mins when no more fizzing was observed. (a) (i) Sketch the graph that you would obtain from the data collected. Name the axes correctly and label the curve as X. [2] (ii) The experiment was repeated a second time. This time the experiment was conducted with the acid warm to 50 °C. The volume and concentration of the acid remains the same for the two experiments. Sketch the graph that you would