CHIJ 4NA Sci (Chem) Prelim 2023 P4

Index Number Class Name CHIJ ST JOSEPH’S CONVENT PRELIMINARY EXAMINATIONS NA SCIENCE (CHEMISTRY) Paper 4 Chemistry Secondary 4 Normal (Academic) NA 5105/04 5107/04 Thursday, 27 July 2023 Paper 3 and 4: 1 hour and 15 minutes READ THESE INSTRUCTIONS FIRST Write your index number, class and name on all the work you hand in. Write in dark blue or black pen. You may use a soft pencil for any diagrams, graphs or rough working Do not use staples, paper clips highlighters, glue or correction fluid. Paper 4: Answer all questions in Section A and any two questions in Section B. The use of an approved scientific calculator is expected, where appropriate. In calculation, you should show all the steps in your working, giving your answer at each stage. You are advised to spend no longer than 30 minutes on Paper 3. You may proceed to answer Paper 4 as soon as you have completed Paper 3. A copy of the Periodic Table is printed on page 14. At the end of the examination hand in your answers to Paper 3 and Paper 4 separately. The number of marks is given in brackets [ ] at the end of each question or part question. FOR EXAMINER’S USE Paper 3 / 20 Paper 4 / 30 TOTAL / 50 This document consists of 14 printed pages.

2 Section A (14 marks) Answer all questions in the spaces provided. 1 Substances may be described as containing A a pure element, B a pure compound, C a mixture of elements, D a mixture of compounds. Complete the table by writing the letter corresponding to the most appropriate description for each of the substances listed. The first one has been completed for you. substance description carbon dioxide B water bitumen steel [2] [Total: 2]

3 2 Magnesium chloride can be used as a mineral supplement to prevent and treat low amounts of magnesium in the blood. (a) State the formula of magnesium chloride. ……………………………………………………………………………….. [1] (b) Describe, in terms of electrons, how a chlorine atom becomes a chloride ion. ……………………………………………………………………………….. ……………………………………………………………………………….. [1] (c) Magnesium chloride has a high melting point. Explain this using the structure and bonding found in magnesium chloride. ……………………………………………………………………………….. ……………………………………………………………………………….. ……………………………………………………………………………….. ……………………………………………………………………………….. [2] [Total: 4]

4 3 Some gases found in air pollute the environment. (a) Complete the table to show one major source of the atmospheric pollutant in the table. Table 3.1 atmospheric pollutant source carbon dioxide combustion of fossil fuels sulfur dioxide [1] (b) Sulfur dioxide dissolves in raindrops to produce ‘acid rain’. (i) Write a word equation to show the conversion of the sulfur dioxide in a raindrop into a compound that causes acid rain. ………………………………………………………………………… [1] (ii) The Eiffel Tower is made of iron. State the effect that acid rain would have on the Eiffel Tower. ………………………………………………………………………… [1] (c) One of the gases in Table 3.1 has been wrongly classified as an atmospheric pollutant. Name the gas and explain why it is not an atmospheric pollutant. ……………………………………………………………………………….. ……………………………………………………………………………….. [1] [Total: 4]

5 4 The diagram below shows some reactions involving compounds P, Q, R and S. (a) By looking at the reaction with aqueous bromine, state which homologous series hydrocarbon P belongs to. ……………………………………………………………………………….. [1] (b) (i) Hydrocarbon Q has 2 carbon atoms. Draw the full structural formula of hydrocarbon Q. [1] (ii) Hence, predict the observation when hydrocarbon Q is added to aqueous bromine. ………………………………………………………………………… [1] (c) Identify compounds R and S. ……………………………………………………………………………….. [1] [Total: 4]

6 Section B (16 marks) Answer any two questions from this section in the spaces provided. 5 (a) Tartrazine, C16H9N4Na3O9S2, is an orange colouring that can be added to food and drinks. Orangine is an orange squash , which is often used to make orange flavoured drinks. A label from a bottle of Orangine is shown. Orangine is tested for tartrazine by a food inspector. The following procedure is used. • A more concentrated solution of Orangine is made. • A pencil line is drawn on a piece of filter paper. • A drop of the concentrated Orangine and a drop of tartrazine solution are placed at different points on the pencil line. • The filter paper is placed in a beaker of water and left for one hour. The results of the test are as shown: ORANGINE Rich in Vitamin C Contains no tartrazine Dilute by mixing 1 part of squash with 4 parts water water

7 (i) State whether Orangine is a mixture of compounds or is a single compound. Give a reason for your answer. ………………………………………………………………………… ………………………………………………………………………… [1] (ii) Name the procedure used by the food inspector to test the Orangine. ………………………………………………………………………… [1] (iii) What would happen if the water in the beaker was higher than the pencil line? ………………………………………………………………………… ………………………………………………………………………… [1] (iv) Is the label from the bottle of Orangine accurate? Explain your answer. ………………………………………………………………………… ………………………………………………………………………… [1] (v) How much Orangine drink is made when 75 cm 3 of Orangine squash is diluted with water? Use the information from the label. volume = ………………… cm3 [1] (vi) Calculate the relative molecular mass of Tartrazine, C16H9N4Na3O9S2. [relative atomic masses, Ar: C, 12; H, 1; N, 14; Na, 23; O, 16; S, 32] relative molecular mass = ……………………… [1]

8 (b) Tartrazine has a melting point of 300 C. Describe the arrangement and movement of the particles of tartrazine at 30 C. Arrangement: ……………………………………………………………………………..... ……………………………………………………………………………..... Movement: ……………………………………………………………………………..... ……………………………………………………………………………..... [2] [Total: 8]

9 6 A farmer wants to grow peas in a field. The farmer tested the soil and finds it has a pH of 6.0. Peas require soil that is slightly alkaline. (a) (i) Is the soil in the field suitable for peas to grow? Explain. ………………………………………………………………………… ………………………………………………………………………… [1] (ii) The farmer added some calcium hydroxide to make the soil suitable for growing peas. Explain, in terms of the chemistry involved, the effect calcium hydroxide has on the soil. ………………………………………………………………………… ………………………………………………………………………… [1] Ammonium sulfate , (NH 4)2SO4, is a common fertiliser that can also be added to soil to improve crop yield. On warming, 0.5 g of ammonium sulfate reacts with excess aqueous sodium hydroxide to produce a salt, water, and ammonia gas. (b) (i) Construct a balanced chemical equation for the above reaction. ………………………………………………………………………… [2] (ii) Calculate the relative molecular mass of ammonium sulfate , (NH4)2SO4. [relative atomic masses, Ar: N, 14; H, 1; S, 32; O, 16] relative molecular mass = ……………………… [1] (iii) Calculate the number of moles in 0.5 g of ammonium sulfate. number of moles = ……………………… mol [1]

10 (c) Aqueous sodium hydroxide also reacts with aqueous nitric acid to form salt R and water. The salt solution formed was found to be contaminated with some sand particles. Describe how you could obtain a pure, dry sample of R from the mixture. …………………………