Question

Reactant ‘A’ underwent a decomposition reaction. The concentration of ‘A’ was measured periodically and recorded in the table given below:

Time (Hours)	[A] (M)
0	0.40
1	0.20
2	0.10
3	0.05

Based on the above data, predict the order of the reaction and write the expression for the rate law.

Hint:

For first-order reactions, the natural logarithm of concentration vs time should yield a straight line.

Answer 1

To determine the order of the reaction, we can use the integrated rate law equations for different reaction orders.
By plotting the concentration vs time data, we can determine the reaction order.
A straight line for a plot of ln[A] vs time indicates a first-order reaction.
From the given data, we confirm that the reaction is first-order.
Thus, the rate law is: \[ \text{Rate} = k[A] \]