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1 This revision booklet contains questions from the Coordinated examinations from At the end of each question you will find a code corresponding to the year that the question came from. example the first question has 0654/31/M/J/11. This means coordinated course (0654) paper 3 sample 1 (31) May June (M/J summer), 2011 (11). these codes to find the relevant mark schemes on the web // Teacher Mr Stocker Ms Bisby Mr Stocker Ms Bisby Mr Stocker Ms Bisby Topic Bonding Identification of ions (Prac) Stoichiometry Ions 2 and gas collection (Prac) Rates of reactions Rates of reactions (Prac) Day Tuesday 28 th Feb L5 Wednesday 29 th Feb L5 Tuesday 13 th March L5 Wednesday 14 th March L5 Tuesday 3 rd April L5 Wednesday 4 th April L5 When tackling questions there are a few helpful tips to follow: Pre readings Chapter 3 P290 Chapter 5 Question Number Q4 0654/31/O/N/10 Q6-0654/03/M/J/08 Q3 0654/61/O/N/10 Q3 0654/03/O/N/09 P288, 290 Q2 0653/06/O/N/07 Chapter 10 Q4 0654/31/M/J/10 Chapter 10 Q1 0654/31/O/N/10 Q5-0654/62/M/J/ Underline the command words. These have specific meanings and give you an idea about how to answer the question and the amount of detail required. These terms can be found in glossary 6 of the syllabus. Look at the number of marks allocated. Always give more points than required. If the question is worth 3 marks, give 4 or 5 points. bullet points when answering long questions. This helps to organise your work into a logical sequence and helps to keep a track of how many different points you have made. When drawing a table remember to separate the boxes with ruled lines, include headings and units. When describing graphs, always make statements that include both the independent and dependent variable. Back this up with quoting figures from the graph. When drawing graphs include an even scale, labelled axis with units and join the plotted points with a smooth curve (for Chemistry only) Every couple of years there are small changes to the syllabus. As such, some of the proceeding questions contain sections that are no longer relevant. These have been left in this booklet as they often give context to the question. If something looks unfamiliar use your checklists or the syllabus to see if it is relevant to you. Although these questions have been put into topic groups, you will notice that sometimes a question merges with other chemistry topics, and even biology and physics topics. This is the nature of the Coordinated Science exam and you need to practice these as well. Good luck, study hard and remember Science is very cool!

2 10 4 In jet engines, hydrocarbon molecules from the jet fuel mix with air and burn. This releases a large amount of energy and produces a mixture of waste gases. These waste gases pass out through the back of the jet engine into the atmosphere. waste gases air jet engine (a) Fig. 4.1 shows a molecule of octane, which is a typical hydrocarbon molecule in jet fuel. octane key carbon atom hydrogen atom (i) State the chemical formula of octane. Fig. 4.1 (ii) Complete the word equation below for the complete combustion of octane. octane + + (b) The mixture of waste gases coming from the jet engine contains a large amount of the free element nitrogen, N 2, which exists naturally in the air. The atoms in a nitrogen molecule are held together by a triple covalent bond as shown in the displayed formula below. N N (i) State the number of outer electrons in a single nitrogen atom. UCLES /31/O/N/10

3 11 (ii) Complete the bonding diagram below to show how the outer electrons are arranged around the atoms in a nitrogen molecule. N N (iii) The temperature inside the jet engine is very high. Suggest why most of the nitrogen molecules which pass through the engine do not break up into individual atoms. UCLES /31/O/N/10 [Turn over

4 12 (c) Table 4.1 shows information about some metallic materials. Table 4.1 material strength density mild steel very high very high aluminium low low duralumin (an aluminium alloy) very high low (i) Duralumin is used in the manufacture of aircraft. Explain why the properties of this material make it suitable for this purpose. (ii) A sample of duralumin has a mass of g and contains 1.73 moles of aluminium. Calculate the percentage by mass of aluminium in this sample of duralumin. Show your working. [3] UCLES /31/O/N/10

5 7 3 The science teacher gives a student a sample of compound X. It is a light green crystalline solid. The student carries out the experiments shown in Table 3.1 to find out what compound X contains. Complete Table 3.1. Table 3.1 test observations conclusions (a) Add compound X to aqueous sodium hydroxide and warm the mixture. A strong smelling gas is given off. The gas turns litmus The gas is Compound X contains ions. (b) Dissolve compound X in water. Divide the resulting solution X into three parts. (i) To the first part of solution X, add aqueous sodium hydroxide. There is a green precipitate which turns brown after standing in air for a few minutes. The precipitate is hydroxide. This turns to hydroxide by a process known as (ii) To the second part of solution X, add dilute hydrochloric acid followed by aqueous Compound X contains sulfate ions. (iii) To the third part of solution X, add dilute acid followed by aqueous No precipitate is formed. Compound X does not contain chloride ions. UCLES /61/O/N/10 [Turn over

6 13 6 Fig. 6.1 shows some natural processes which occur on and under the Earth's surface. rock A water flowing to sea sea molten rock rock C formed from other rocks by heat and pressure Fig. 6.1 rock B forming in layers and then being pushed into the earth (a) (i) State which rock, A, B or C, was formed when a hot liquid cooled and changed into a solid. (ii) Rock B formed in layers from tiny pieces of solid (sediment) which were washed down to the sea by rivers and compressed. The sediment was produced from rock A whose surface had been damaged by weathering. Describe one way in which the surface of rock A could have been weathered. UCLES /03/M/J/08 [Turn over

7 14 (b) A sample of the water flowing into the sea, as shown in Fig. 6.1, was taken to a laboratory for testing. A student observed a drop of water under a microscope. Fig. 6.2 shows a labelled diagram of what he saw. water dispersed solid particles Fig. 6.2 Explain why the water sample looked cloudy and not transparent. You may wish to add some light rays to Fig. 6.2 to help you answer this question. (c) The element bromine is extracted from concentrated solutions of bromine compounds. The reaction between chlorine and sodium bromide solution produces bromine. chlorine + sodium bromide sodium chloride + bromine (i) Explain why chlorine but not iodine reacts with sodium bromide. UCLES /03/M/J/08

8 15 (ii) In the boxes below, draw diagrams of a chlorine atom and a bromide ion, showing only the electrons in the outer shells. chlorine atom bromide ion Cl Br (iii) Describe how the numbers of outer electrons of the particles you have drawn in (ii) change during the reaction of chlorine with sodium bromide. (d) A solution of bromine is used to discover whether a compound is a saturated or unsaturated hydrocarbon. Explain the meanings of the words saturated and unsaturated hydrocarbon. UCLES /03/M/J/08 [Turn over

9 2 The teacher gave two students a set of three colourless solutions, labelled X, Y and Z. He also gave them solution P which is an indicator. Solution P is colourless in an acidic solution but pink in an alkaline solution. 4 The students added solution P to samples of the solutions X, Y and Z. Fig. 2.1 shows the results. solution X solution Y solution Z colourless pink pink Fig. 2.1 (a) Decide whether solutions X, Y and Z are acidic or alkaline. solution X solution Y solution Z (b) The students wanted to deduce the name of the acid. They carried out a test that showed that the acid contained sulphate ions. (i) Name the reagent that they added to the acid. (ii) Describe what they observed when this reagent was added to the acid. (iii) Name the acid. (c) The students placed about 1 cm 3 of solution Y in a test-tube and added one drop of solution P. Then they added solution X, a few drops at a time. After a few drops had been added there was no change in colour, but when more drops of solution X had been added, the colour changed. (i) There was no change in colour when the first few drops of solution X had been added. Why was this? UCLES /06/O/N/07

10 5 (ii) Suggest how the colour changed when more drops of solution X were added. The colour changed from to (iii) What kind of reaction took place between solution X and solution Y? (d) Fig. 2.2 shows the result of two more experiments that the students carried out. Study their observations and then suggest the names of solutions Y and Z. 1 2 test 1 cm 3 of zinc sulphate solution was placed in a test-tube, then solution Y was added a little at a time. 1 cm 3 of solution Z was placed in a test-tube. Then solution X was added. result At first there was a white precipitate that dissolved when more solution Y was added. The mixture bubbled. A gas was given off that turned limewater milky Fig. 2.2 name of solution Y name of solution Z UCLES /06/O/N/07 [Turn over

11 6 3 Some types of fertiliser have the letters NPK on the package label, indicating the chemical symbols of three elements contained in the fertiliser. N : P : K (a) State and explain which of the elements shown in the name NPK contains atoms that have their electrons arranged as shown in Fig Fig. 3.1 element explanation (b) Plants need nitrogen in order to produce amino acids. Name the three elements, other than nitrogen, which are present in all amino acid molecules. UCLES /03/O/N/09

12 7 (c) Ammonia is an important compound that is used in the manufacture of fertilisers. Fig. 3.2 shows a simplified diagram of the type of reaction vessel that is used in the production of ammonia. nitrogen hydrogen iron catalyst mixture of gases containing 15 % by mass of ammonia (the yield of ammonia = 15 %) Fig. 3.2 (i) The equation below shows what happens on the surface of the iron catalyst. The equation is not balanced. Balance the equation. N 2 + H 2 NH 3 (ii) The yield of ammonia in this reaction vessel is 15%. This means that the mixture of gases coming out of the reaction vessel contains 15% by mass of ammonia. State and explain which gases account for most of the remaining 85% of the gas mixture. UCLES /03/O/N/09 [Turn over

13 8 (iii) Research chemists and engineers have investigated the effects of temperature and pressure on the yield of ammonia. Fig 3.3 shows the results of their investigations. yield of ammonia % C 400 C 600 C pressure / atmospheres Fig. 3.3 The engineers running the factory want to increase the yield of ammonia. the information in Fig. 3.3 to suggest two ways in which this could be done. 1 2 (d) In an ammonia factory, 1000 kg of gas mixture leave the reaction vessel every minute. In this factory the yield of ammonia is 17 %. Calculate the number of moles of ammonia which leave the reaction vessel every minute. Show your working. [relative atomic masses, A r : N=14; H=1] 1 kg = 1000 g [4] UCLES /03/O/N/09

14 8 4 A student used the apparatus shown in Fig. 4.1 to investigate the reaction between a solution of an acid A and 20.0 cm 3 of a solution of the alkali, potassium hydroxide. acid A (0.2 mol / dm 3 ) tap beaker 20 cm 3 of potassium hydroxide solution (0.5 mol / dm 3 ) Fig. 4.1 temperature sensor computer Fig. 4.2 shows how the temperature of the mixture changed as the acid was added to the alkali in the beaker. temperature volume of acid added / cm 3 Fig. 4.2 UCLES /31/M/J/10

15 9 (a) (i) State why the temperature of the mixture increased when the acid was first added to the alkali. (ii) Explain how the information in Fig. 4.2 shows that it took 25.0 cm 3 of the acid to neutralise 20.0 cm 3 of the potassium hydroxide solution. (b) In the experiment, the concentrations of acid A and the potassium hydroxide solution were 0.2 mol / dm 3 and 0.5 mol / dm 3 respectively. (i) the equation moles (dissolved) = volume (dm 3 ) x concentration (mol / dm 3 ) to calculate the number of moles of both acid A and potassium hydroxide which neutralised each other in this reaction. moles of acid A moles of potassium hydroxide (ii) State the number of moles of acid A which would be needed to neutralise one mole of potassium hydroxide. Explain your answer briefly. moles of acid A explanation (iii) Write the ionic chemical equation which represents what happens when an aqueous acid reacts with aqueous alkali. UCLES /31/M/J/10 [Turn over

16 + 10 (c) In the year 1807, metallic potassium was obtained from potassium hydroxide. Fig. 4.3 shows a simplified diagram of the apparatus that was used. high voltage battery platinum wire molten potassium hydroxide platinum plate heat Fig. 4.3 Bubbles of gas were seen where the platinum wire touched the top of the potassium hydroxide. Shiny beads of molten potassium were seen where the potassium hydroxide rested on the platinum plate. (i) Name the process shown in Fig (ii) Explain why the potassium metal formed where the potassium hydroxide touched the platinum plate. Your answer should include the ideas of electrical charge, atoms, ions and electrons. [3] UCLES /31/M/J/10

17 2 1 Fig. 1.1 shows the apparatus a student used to study the rate of reaction between 1.0 g of powdered metal and dilute hydrochloric acid. test-tube full of water conical flask 1.0 g powdered metal water dilute hydrochloric acid Fig. 1.1 When the student tilted the conical flask, the acid mixed with the powdered metal. If a reaction occurred, any gas which was produced collected in the test-tube, pushing the water out. The student measured the time taken for the test-tube to fill with gas. (a) (i) Name the gas produced when metals react with dilute hydrochloric acid. (ii) State the formula of the ion which is present in relatively high concentrations in all acids. (b) The student used the apparatus and method described above to compare the rates of reaction between dilute hydrochloric acid and three powdered metals, X, Y and Z. The results the student obtained are shown in Table 1.1. Table 1.1 metal mass of metal / g time for gas to fill the test-tube / seconds X Y Z UCLES /31/O/N/10

18 3 (i) The student was careful to ensure that the only variable (factor) which differed between the experiments was the type of metal. State two variables, other than the mass and surface area of the metals, which the student must keep the same in each experiment. 1 2 (ii) Explain how the results show that the rate of reaction was the lowest when metal X was used. (iii) The student repeated the experiment with metal Y but this time he used a single piece of metal which had a mass of 1.0 g. State how the rate of reaction would differ from the experiment in which 1.0 g of powdered metal was used. Explain your answer in terms of the collisions between atoms in the surface of the metal and ions in the solution. [3] UCLES /31/O/N/10 [Turn over

19 4 (c) When magnesium reacts with dilute hydrochloric acid, HCl, one of the products is magnesium chloride, MgCl 2. (i) Construct a balanced symbolic equation for this reaction. (ii) Magnesium chloride is a compound which causes hardness in water. Describe briefly how the process of ion exchange is used to soften hard water. You may draw a simple diagram if it helps you to answer this question. UCLES /31/O/N/10

20 12 5 A student is investigating the rate of reaction between magnesium and dilute hydrochloric acid. She does several experiments using different concentrations of the acid with the same lengths of magnesium ribbon. Fig. 5.1 shows the apparatus she is using. measuring cylinder magnesium ribbon and dilute hydrochloric acid Fig. 5.1 She measures out the volume of dilute hydrochloric acid for experiment 1, shown in Table 5.1, and places it in the test-tube. She adds water to make the total volume of liquid equal to 20 cm 3. She cuts a 6 cm length of magnesium ribbon, puts it in the test-tube and quickly replaces the stopper and the delivery tube. After 40 seconds she measures the volume of hydrogen in the measuring cylinder and records it in Table 5.1. She carries out experiments 2, 3, 4 and 5 in the same way. UCLES /62/M/J/10

21 13 experiment no. volume of acid / cm 3 Table 5.1 volume of water / cm 3 concentration of the acid in the test-tube / mol / dm 3 volume of hydrogen after 40 s / cm (a) Fig. 5.2 shows the measuring cylinder readings for experiments 2, 3 and 5. Read the volumes of hydrogen and record the readings in Table 5.1. [3] volume of hydrogen after 40 s experiment volume of hydrogen after 40 s experiment volume of hydrogen after 40 s experiment 5 Fig. 5.2 (b) Calculate the concentration of the acid in the test-tube used in experiments 3, 4, and 5. Complete Table 5.1. UCLES /62/M/J/10 [Turn over

22 14 (c) Plot a graph of volume of hydrogen / cm 3 (vertical axis) against concentration of hydrochloric acid in mol / dm 3 on the graph grid. Draw the best straight line and extend it to pass through the origin. [3] UCLES /62/M/J/10

23 15 (d) (i) To make the experiment fair, it is important for the student to use the same length of magnesium ribbon in all of these experiments. Suggest two reasons for this. reason 1 reason 2 (ii) What does the shape of the graph show about the relationship between the volume of hydrogen given off in 40 seconds and the concentration of the acid used? UCLES /62/M/J/10 [Turn over