Integrated Rate Law Method for Determining Reaction Order and Rate Constant (10

Question

Integrated Rate Law Method for Determining Reaction Order and Rate Constant (10 points) The hydrolysis of sucrose to form two glucose molecules can be followed by spectrophotometrically measuring the concentration of sucrose as a function of time. From the following measurements, determine the reaction order with respect to sucrose and the rate constant using the integrated rate law method. Attach a sheet showing a linear regression to the data transformed according to the appropriate integrated rate law Time (min) [sucrosel (M) 0 14 39 60 80 110 140 170 210 0.316 0.3 0.274 0.256 0.238 0.211 0.19 0.17 0.146

Explanation / Answer

K0 = (0.316-0.3)/14 = 0.0011 M.sec-1

K0 = (0.316-0.274)/39 = 0.001 M.sec-1

K0 = (0.316-0.256)/60 = 0.001 M.sec-1

K0 = (0.316-0.238)/80 = 0.000975 M.sec-1

as Ko is different at different time intervals,it is not zero order.

K1 = (1/t)ln(a/a-x)

   = (1/14)ln(0.316/0.3)

= 0.0037 min-1

K1 = (1/3)9ln(0.316/0.274)

    = 0.00366 min-1

K1 = (1/80)ln(0.316/0.238)

    = 0.00354 min-1

as k1 is different,it is not first order

K2 = 1/t[1/a-x - 1/a]

   = (1/14)((1/0.3)-(1/0.316))

   = 0.012

K2 = (1/39)((1/0.274)-(1/0.316))

   = 0.012

k2 = (1/60)((1/0.256)-(1/0.316))

   = 0.012

as K2 is constant it is a second order reaction.

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