|Class 12 Chemistry Chemical Kinetics||Zeroth order reaction|
Zeroth order reaction
If the rate of reaction is independent of concentration of the reactant participating in the reaction then the reaction is called Zeroth order reaction.
A --> B
At time t = 0 concentration of A (reactant) is a and B (product) is 0. At time t = t the concentration of A (reactant) is (a-x) and that of B (product) is x.
-d[A]/dt = k0[A]0 => dx/dt = k0(a-x)0
dx/dt = k0
∫ 0x dx =k0 ∫0 x dt
X = k0t
PROBLEM. The decomposition of NH3on platinum surface is zero order reaction. What are the rates of production of N2and H2if k = 2.5 x 10-4mol-1L s-1?
SOLUTION. 2NH3 --> N2 + 3H2
Rate of zero order reaction
-1/2 (d[NH3]/dt) = d[N2]/dt = 1/3 (d[H2]/dt)
-1/2 (d[NH3]/dt) = d[N2]/dt = 1/3 (d[H2]/dt)= k = 2.5 x 10-4 mol L-1 s-1
Rate of production of N2
d[N2]/dt = 2.5 x 10-4 mol L-1 s-1
Rate of production of H2
d[H2]/dt = 3 x 2.5 x 10-4 mol L-1 s-1