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Question 1
A student mixes anhydrous cobalt chloride with water to form hydrated cobalt chloride. The word equation for the reaction is below. anhydrous cobalt chloride (blue) + water ⇋ hydrated cobalt chloride (pink) |
a) | What does the ⇋ symbol mean?
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b) | What will the student observe when the anhydrous cobalt chloride is mixed with water?
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c) | The forward reaction is exothermic. Explain the effect of increasing the temperature of reaction on the yield of hydrated cobalt chloride.
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Question 2
This question is about the industrial production of methanol (CH3OH). |
a) | Methanol is produced by reacting carbon monoxide with hydrogen. Write a balanced chemical equation for this reversible reaction.
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b) | Calculate how many moles of hydrogen are required to completely react with 5 x 103 moles of carbon monoxide.
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c) | In industry the process is carried out at a pressure of 100 atmospheres. Explain what happens if the reaction is carried out at a lower pressure than this.
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d) | A catalyst can be used in the production of methanol from carbon monoxide and hydrogen. Explain the role of the catalyst in this reaction.
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Question 3
This question is about the industrial production of ethanol. |
a) | State the chemical formula of ethanol.
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b) | The chemical equation for the production of ethanol is below: C2H4(g) + H2O(g) ⇋ C2H5OH(g) The table shows the bond energies for this reaction. Calculate the energy change during the production of ethanol and determine if the forward direction is endothermic or exothermic.
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c) | Describe the effect of increasing the temperature on:
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d) | Explain the effect of using a high pressure on:
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Question 4
This question is about the production of hydrogen by reacting methane with steam. |
a) | Write a balanced chemical equation for the reversible reaction between methane and steam to produce carbon monoxide and hydrogen.
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b) | The reaction has a ΔH value of + 206 kJ/mol. Explain what this means.
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c) | The reaction is usually completed at 700°C and 5 atmospheres. State the effect on the change of yield of hydrogen at equilibrium if the pressure is decreased to 2 atmospheres.
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d) | Explain what happens to the dynamic equilibrium when the temperature is halved.
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Question 5
This question is about the reversible reaction between nitrogen dioxide and dinitrogen tetraoxide. The equation for the reaction is below. 2NO2(g) ⇋ N2O4(g) ΔH = -58 kJ/mol |
a) | What does the ⇋ symbol mean? A the reaction is exothermic B the reaction is endothermic C the reaction is reversible D the reaction is a displacement reaction
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b) | Which of the following would not shift the dynamic equilibrium to the right? A increasing pressure B decreasing temperature C increasing temperature
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c) | Explain what is meant by the term activation energy.
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d) | Another reaction is completed in the presence of a catalyst. Explain the role of a catalyst in a chemical reaction.
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Question 6
This question is bout the reaction between hydrogen and iodine to form hydrogen iodide. |
a) | Write a balanced chemical equation for the reversible reaction between hydrogen (H2) and iodine (I2) to form hydrogen iodide (HI).
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b) | The statements below refer to the reaction between hydrogen and iodine. The enthalpy change for the reaction ΔH = -9.48 kJ/mol. Tick one box in each row to show whether each of the following statements is true or false.
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c) | Explain, with reference to particle theory, how increasing the temperature will affect:
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d) | Draw a reaction profile to show the forward reaction between hydrogen and iodine to form hydrogen iodide.
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Question 7
A student is investigating the decomposition of ammonium chloride. NH4Cl(s) ⇋ NH3(g) + HCl(g) |
a) | State what the ⇋ symbol means.
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b) | The student soaks one piece of cotton wool with hydrochloric acid, and one piece of cotton wool with ammonia. The two pieces of cotton wool are placed inside a tube and sealed at each end with a bung, as shown in the diagram below. After a few minutes, a ring of ammonium chloride forms in the tube. Explain why the ring has not formed in the centre.
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c) | Explain how increasing the pressure would change the yield of ammonium chloride.
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Question 8
This question is about the production of hydrogen gas from methane and steam. The chemical equation for the reaction is below. CH4(g) + H2O(g) ⇋ CO(g) + 3H2(g) ΔH = 160.5 kJ/mol |
a) | Explain what is meant by the term 'dynamic equilibrium'.
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b) | Tick one box in each row to show which changes would increase the yield of hydrogen.
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c) | The temperature and pressure of the reaction are increased. Explain why it is difficult to predict how the percentage yield of hydrogen will change.
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Question 9
A student is investigating decomposition of hydrogen peroxide (H2O2). The students method is shown below:
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a) | The graph below shows how the volume of gas produced varied with time. Describe how the rate of oxygen produced varied during the 20 minute experiment.
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b) | The student draws a tangent on the graph at 8 minutes. Calculate the rate of reaction in cm3/min at 8 minutes. Give your answer to 2 decimal places.
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c) | State the rate of oxygen production at 15 minutes.
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