HARDINTEGERJEE Mains ChemistryPhysical ChemistryChemical kineticsAchiever Section
Hydrolysis of methyl acetate in aqueous solution has been studied by titrating the liberated acetic acid against sodium hydroxide. The concentration of the ester at different times is given below. t/min C/mol L-1 0.8500 0.8004 0.7538 0.7096 The concentration of water remains nearly constant (55 mol L-1), during the course of the reaction. What is the value of k’ in this equation ? Rate = k’ [CH₃COOCH₃] [H₂O] (a) 3.64 10 mol Lmin x (b) 3.75 10 mol Lmin x (c) 4.7 10 mol Lmin x (d) 2.64 10 mol Lmin x
Answer
A
Explanation
For pseudo first order reaction, the reaction should be first order with respect to ester when [H₂O] is constant. The rate constant k for pseudo first order reaction is 0 2 C 2.303 k log where k k' H O t C From the above data we note t/min C/mol L-1 k/min-1 0 30 60 90 0.8500 0.8004 0.7538 0.7096 - 2.004 x 10-3 2.002 x 10-3 2.005 x 10-3 We can now determine k’ from 3 1 2 1 3 1 5 1 1 k ' H O 2.004 10 min k ' 55molL 2.004 10 min k ' 3.64 10 mol Lmin x x x
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