11177 13 Ethyl ethanoate is hydrolysed in alkaline conditions as follows: CH3COOC2H5  +  OH−  "  CH3COO−  +  C2H5OH (a) Explain, giving experimental details, how you would follow the rate of this reaction with respect to hydroxide ions using pH and how you would use your results to find the order of the reaction with respect to hydroxide ions. In this question you will be assessed on using your written communication skills including the use of specialist scientific terms. [6] (b) The following results were obtained for the reaction. [CH3COOC2H5] /mol dm−3 [OH−] /mol dm−3 initial rate of the reaction /mol dm−3 s−1 0.152 0.038 1.13 × 10−2 0.038 0.076 5.65 × 10−3 0.019 0.152 5.65 × 10−3 11177 [Turn over (i) Deduce the rate equation for the reaction. [2] (ii) Calculate, to three significant figures, the value of the rate constant and state its units. [2] (iii) State and explain the effect of increasing the temperature on the value of the rate constant. [2] (c) Ethanoic acid reacts with butan-1-ol to form the ester butyl ethanoate as follows: CH3COOH(l)  +  C4H9OH(l) ?  CH3COOC4H9(l)  +  H2O(l)  −39.8 kJ mol−1 (i) What mass of butan-1-ol is required to produce 58 g of butyl ethanoate when reacted with 45 g of ethanoic acid in 50 cm3 of water? Give your answer to two significant figures. (Kc = 3.0 at 20 °C; the density of water is 1 g cm−3) [4] 11177 (ii) Suggest and explain the effect of increasing the temperature to 40 °C on the position of the equilibrium. [2] (iii) Explain why the equilibrium constant has no units. [1] (d) The ester tallow is an animal fat which is formed from two molecules of stearic acid, CH3(CH2)16COOH, and one molecule of oleic acid, CH3(CH2)7CHCH(CH2)7COOH. (i) Tallow exists as two isomers. Draw the structure of one isomer of tallow. [2] 11177 [Turn over (ii) Tallow can undergo transesterification. Explain what is meant by the term transesterification. [2] (iii) State two uses of transesterification reactions. [2]