Question

The rate of the second-order decomposition of acetaldehyde (CH3CHO) was measured over the temperature range 700–1000 K, and the rate constants are reported below. Find Ea and A.

Answer 1

Answer:

Explanation:

For a reaction involving the decomposition of  Y  the following data are obtained:

Rate (mo l/L . min)    0.288   0.245  0.202  0.158

[Y]                             0.200    0.170   0.140   0.110

Answer 2

The second order decomposition of acetaldehyde $E_{a}=188kJmol^{-1}$,$A=1.08*10^{12}Lmol^{-1}s^{-1}.$

Explanation:

We point in $k$ against $\frac{1}{t}$ and expect a straight line. The slope is $\frac{E_{a} }{R}$ and the intercept of the extrapolation to $\frac{1}{T}$ =0 is in $A$. After plotting the graph, it is best to do a least squares fit of the data to a straight line. A has the same units s k.

The least squares best fit of the line has slope $-2.265*10^{4}$ and intercept $27.71.$

$E_{a} =2.265*10^{4}K*8.3145JK^{-1} mol^{-1}$

$=188kJmol^{-1}$

$A=e^{27.71}L mol^{-1}s^{-1}$

$=1.08*10^{12}Lmol^{-1}s^{-1}.$