Unit 9 : 9.1&9.2 Name:... Class:.. Date: Paper 2 Excellence International School Chemistry Academic Year 2016-2017 Grade 9 Revision sheet 3 Topic: unit 8 speed of reaction 1 st term 1. A student was investigating the reaction between marble chips and dilute hydrochloric acid. Which changes would reduce the rate of reaction? 2. The solvent ethanol is produced by the fermentation of sugar, using yeast. Which graph correctly shows how the speed of fermentation changes with temperature? Excellence International School chemistry 9 revision sheet 3 1
3. In an experiment using dilute acid and a metal, the speed at which hydrogen is released is measured (curve X on graph). The experiment is repeated but with one of the conditions changed (curve Y on graph). Which changes in condition could result in curve Y? 4. Which changes of condition slow down the reaction between magnesium and air? 1 heating the magnesium to a higher temperature 2 using a higher proportion of oxygen in the air 3 using magnesium ribbon instead of powdered magnesium A 1 only B 2 only C 3 only D 1, 2 and 3 Excellence International School chemistry 9 revision sheet 3 2
5. A student investigates the rate of reaction between marble chips and hydrochloric acid. The loss in mass of the reaction flask is measured. The graph shows the results of two experiments, P and Q. Which change explains the difference between P and Q? A A catalyst is added in P. B A higher temperature is used in P. C Bigger marble chips are used in Q. D Hydrochloric acid is more concentrated in Q. 6. An experiment to determine the rate of a chemical reaction could be carried out using the apparatus shown. Which reaction is being studied? A Cl 2 + 2KBr 2KCl + Br2 B Mg + H2SO4 MgSO4 + H2 C NaCl + AgNO3 NaNO3 + AgCl D NaOH + HCl NaCl + H2O Excellence International School chemistry 9 revision sheet 3 3
7. The equation shows the formation of anhydrous copper(ii) sulfate from hydrated copper(ii) sulfate. Statements 1, 2 and 3 refer to this reaction. 1 Hydrated copper(ii) sulfate is reduced to anhydrous copper(ii) sulfate. 2 The (II) in the name copper(ii) sulfate refers to the oxidation state of the metal. 3 The reaction is reversible. Which statements are correct? A 1 only B 1 and 2 C 2 and 3 D 3 only 8. Heating pink cobalt(ii) chloride crystals forms a blue solid and steam. The blue solid turns pink when water is added. Which terms describe the pink cobalt(ii) chloride and the reaction? 9. The equation shows a reaction that is reversed by changing the conditions. How can the forward reaction be reversed? Excellence International School chemistry 9 revision sheet 3 4
Paper 4 1. Iodine reacts with chlorine to form dark brown iodine monochloride. This reacts with more chlorine to give yellow iodine trichloride. There is an equilibrium between these iodine chlorides. (a) Explain what is meant by equilibrium.......... (b) When the equilibrium mixture is heated it becomes a darker brown colour. Is the reverse reaction endothermic or exothermic? Give a reason for your choice.......... (c) The pressure on the equilibrium mixture is decreased. (i) How would this affect the position of equilibrium and why? It would move to the... reason.... (ii) Describe what you would observe. Excellence International School chemistry 9 revision sheet 3 5
2. The alcohol ethanol can be made by fermentation. Yeast is added to aqueous glucose. Carbon dioxide is given off and the mixture becomes warm as the reaction is exothermic. The graph shows how the rate of reaction varies over several days. (i) Suggest a method of measuring the rate of this reaction.... (ii) Why does the rate increase initially? (iii) Suggest two reasons why the rate eventually decreases.... Paper 6 1. Hydrogen peroxide breaks down to form oxygen. A student investigated the speed of the breakdown of aqueous solutions of hydrogen peroxide of different concentrations, using 1 g of powdered manganese(iv) oxide. The temperature was kept constant at 25 C. She plotted her results on the grid below. Excellence International School chemistry 9 revision sheet 3 6
(a) Draw a straight line graph on the grid. (b) From your graph, work out the speed of the reaction when the concentration of hydrogen peroxide is 0.5 mol /dm3. Show clearly on the grid how you obtained your answer.. (c) Sketch on the grid the graph you would expect if the experiments were repeated at 10 C. (d) (i) What is the function of the manganese(iv) oxide?... (ii) Suggest the effect of repeating the investigation using 1g of lumps of manganese(iv) oxide. Explain your answer. effect... explanation... Excellence International School chemistry 9 revision sheet 3 7