JEE Advanced · 2010 · 11 Apr 2010 · Paper 1 · Chemical Kinetics

The concentration of

R

in the reaction

R \to P

was measured as a function of time and the following data is obtained:

[R] (molar)	1.0	0.75	0.40	0.10
t(min.)	0.0	0.05	0.12	0.18

The order of the reaction is

Answer: 0

Solution

To determine the order, we check if the rate constant is consistent for different orders.

For zero-order kinetics:

k = \frac{[ R ] _{0} - [ R ]}{t}

Using first two data points:

k_{1} = \frac{1.0 - 0.75}{0.05} = \frac{0.25}{0.05} = 5 mol L^{- 1} min^{- 1}

Using first and third data points:

k_{2} = \frac{1.0 - 0.40}{0.12} = \frac{0.60}{0.12} = 5 mol L^{- 1} min^{- 1}

Using first and fourth data points:

k_{3} = \frac{1.0 - 0.10}{0.18} = \frac{0.90}{0.18} = 5 mol L^{- 1} min^{- 1}

Since the rate constant is consistent across all data points, the reaction is zero-order.

JEE Advanced · 2010 · 11 Apr 2010 · Paper 1 · Integer answer