(ii) Zero order reaction means that the rate of the reaction is proportional to zero power of the concentration of reactants. Consider the reaction,
At t = 0, the concentration of the reactant R = [R]0, where [R]0 is
initial concentration of the reactant.
Substituting in equation (1)
[R]0 = –k × 0 + I
[R]0 = I
Substituting the value of I in the equation (1)
[R] = -kt + [R]0.............(2)
Comparing (2) with equation of a straight line,
y = mx + c, if we plot [R] against t, we get a straight
line (Figure) with slope = –k and intercept equal
This reaction follows second order kinetics.
So that, the rate equation for this reaction will
Rate, R = k[X]2 .............(1)
Let initial concentration is x mol L−1,
Plug the value in equation (1)
Rate, R1 = k .(a)2
Given that concentration is increasing by 3 times so new concentration will 3a mol L−1
Plug the value in equation (1) we get
Rate, R2 = k (3a)2
We have already get that R1 = ka2 plus this value we get
R2 = 9 R1
So that, the rate of formation will increase by 9 times.
Rate = k[A]2
If concentration of X is increased to three times,
Rate = k[3A]2
or Rate = 9 k A2
Thus, rate will increase 9 times.