Answer to Question #70722 in Chemistry for order of reaction

Question

The Half life period for catalytic decomposition of AB3 at 50mm is found to be 4 hours and at 100mm it is 2 hours. the order of reaction is ?

Answer 1

Half-life period of a reaction of an order n is related to initial concentration by the expression:

t_(1⁄2)∝1/(C_0^(n-1) ).
Thus, given initial concentration 50mm and 100mm and half-life time 4h and 2h, respectively:
〖(t_(1⁄2))〗_1/〖(t_(1⁄2))〗_2 =〖(100)〗^(n-1)/〖(50)〗^(n-1) ;4/2=〖(2)〗^(n-1);n-1=1;n=2.

It is a reaction of 2nd order.