<p> C. Y. Yeung (AL Chemistry)</p><p>F 7 Revision Exercise (Chemical Equilibria)</p><p>Name: ______Class: ______( ) Date: ______</p><p>1. The industrial preparation of methanol can be represented by the following equation: catalyst</p><p>CO(g) + 2H2(g) CH3OH(g)</p><p>The graph below shows the mole percentage of methanol in the reaction mixture against time at the same pressure but at two different temperatures:</p><p> mole % of methanol in the reaction mixture</p><p>100 2000C E D</p><p>0 50 400 C B C</p><p>0 A time 0 (a) With reference to the graph, answer the following questions: (1) What difference between the two initial rates of reaction can be deduced? Explain your deduction.</p><p>(2) Why do both curves eventually become horizontal?</p><p>(3) Explain whether the reaction for the production of methanol is exothermic or endothermic.</p><p>(b) At a given temperature and pressure, how would an increase in the amount of CO in the system affect the yield of methanol? Explain your answer.</p><p>1/3 C. Y. Yeung (AL Chemistry)</p><p>(c) On the above graph, sketch and label two curves which would be obtained if the process were carried out under the same conditions as those for the curve ABC, except that: (1) no catalyst is used (label this curve as I). (2) a higher pressure is used (label this curve as II).</p><p>2. The energy profiles of the reaction</p><p>A(g) + B(g) C(g)</p><p> under two different catalysts X and Y are represented below. y y g g r r e e n n e e</p><p> l l a a i i t t n n e e system with catalyst X system with catalyst Y t t o o p p</p><p>A, B A, B</p><p>C C (a) What is the effect of increasing temperature on the equilibrium of each system?</p><p>(b) What is the effect of decreasing pressure on the equilibrium of each system?</p><p>(c) Compare the effect of increasing temperature on the rate of reaction in the two system.</p><p>(d) Why could the use of a different catalyst change the order of the reaction?</p><p>3. The manufacture of sulphuric acid by the Contact Process in the presence of finely</p><p>2/3 C. Y. Yeung (AL Chemistry)</p><p> divided vanadium (V) oxide can be represented by the following equation:</p><p>-1 2SO2(g) + O2(g) 2SO3(g) H = -197 kJ mol</p><p>(a) State the effect of an increase in pressure on the system in equilibrium. Briefly explain your answer.</p><p>(b) Explain why the conversion of sulphur dioxide to sulphur trioxide is carried out industrially at a temperature of about 4500C, rather than at lower temperatures.</p><p>(c) What is the purpose of using vanadium (V) oxide, and why should it be finely divided?</p><p>4. The reaction between ethanoic acid and ethanol can be represented by the following equation:</p><p>CH3COOH(l) + CH3CH2OH(l) CH3COOCH2CH3(l) + H2O(l)</p><p>12.01g of ethanoic acid are treated with 4.61g of ethanol in the presence of a catalyst. When the reaction reaches equilibrium at 298K, 5.04g of ethanoic acid are found to have reacted. (a) Calculate the equilibrium constant for the reaction at 298K.</p><p>(b) What additional mass of ethanol would be required in order to use up a further 0.60g of ethanoic acid?</p><p>(c) Would the addition of more of the same catalyst affect the value of Kc? Explain.</p><p>3/3</p>