5CC00035 MAY 2018 QUESTION 10 [20 total marks] The rate law for the formation of methane by the gas-phase thermal decomp

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5cc00035 May 2018 Question 10 20 Total Marks The Rate Law For The Formation Of Methane By The Gas Phase Thermal Decomp 1 (51.33 KiB) Viewed 72 times

5CC00035 MAY 2018 QUESTION 10 [20 total marks] The rate law for the formation of methane by the gas-phase thermal decomposition of ethanal CH3 CHO CH,CHO CH4 + CO has been found experimentally to have three-halves order kinetics with respect to CH2CHO. r = k [CH2CHO]3/2 (a) Find the units for the rate constant. (3 marks) (b) Integrate from the rate law to obtain an equation in terms of [CH:CHO] and time. (5 marks) (c) Derive an equation for t13, the time required to reduce the concentration of ethanol by third. (4 marks) (d) The mechanism of the gas-phase thermal decomposition of ethanal has been suggested in four (1-4) steps as follows: (1) CH, CHO 3 CH2 + CHO (3) (2) CH, + CHỊCH = CH2 + CH CÓ CH3CO" CH3 + CO CH3 + CH3 - CH Prove that the above mechanism can justify the 3/2 order with respect to CH3CHO, and find kr in terms of above rate constants. (8 marks)