## Zero order reaction source  : askIITians

## Zero order reaction-

#### Ex.1) Photochemical reaction between hydrogen and chlorine-

H2  +  Cl2 ——->   2 HCl

Rate = K [H2]0 [Cl2]0 = K

#### Ex.2 ) Decomposition of  ammonia in presence of Mo or W-

2 NH3 ———->  N2    +   3H2

Rate = K [NH3]0  = K

#### Ex.3) Decomposition of N2O on hot Pt-

N2O————> N2 + 1/2 O2

Rate = K [N2O]0  = K

Consider  the reaction,

A——–> B

#### initial conc.     a             0

For zero order reaction,

Rate = dx / dt = K[A]n

n = 0

Rate = dx / dt = K[A]0 = K

dx = K.dt

Taking integration of both sides,

∫ dx = K ∫ dt

x = Kt + C        ———-eq. 1

C is integration constant

If t= 0 , x=0 then C = 0

Now putting the value of  ‘C’ in eq. 1

x = Kt +0

## Characteristics of  zero order reaction-

1) The concentration of the product increases linearly with time. A straight line passing through origin is obtained when  ‘x’  is

plotted against ‘t’ (time).

2) The unit of rate constant ‘K’ is mole litre-1 time-1.

3) The time required for the reaction to be complete i-e time at which [A] is zero.

t = initial conc. / K