A high temperature from a match or spark etc., gives the reactant molecules enough kinetic energy to overcome the activation energy * .
Reactions may commonly be zero order, first order or second order with respect to a particular reactant.
There is now space on the surface of the nickel for new reactant molecules to go through the whole process again.
Not only is the product a stereospecific optical isomer, the reactant is it self a stereospecific geometrical isomer!
However now for the reaction to continue we need a supply of fresh reactant to approach the electrode surface.