Question

Graph between concentration and time for a first order reaction.

Answer 1

A first-order reaction can be defined as a chemical reaction in which the reaction rate is linearly dependent on the concentration of only one reactant.

$\mathrm{Example}:\underset{\mathrm{hydrogen}\mathrm{peroxide}}{2{\mathrm{H}}_2{\mathrm{O}}_2\left(\mathrm{l}\right)}\to \underset{\mathrm{water}}{2{\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right)}+\underset{\mathrm{oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}$

Differential rate law for a First-Order reaction:

Rate = -d[A]/dt = k[A]¹ = k[A] , where

• ‘k’ is the rate constant of the first-order reaction, whose units are s^-1.
• ‘[A]’ denotes the concentration of the first-order reactant ‘A’.
• d[A]/dt denotes the change in the concentration of the first-order reactant ‘A’ in the time interval ‘dt’.

The graphs between concentration and time for a first-order reaction :

Graph explaining the intercept and slope for a first-order reaction: