Answer:
a) 2
b) 1/4
c) 9
Explanation:
a) for a first order reaction in reactant A
r initial = k*[A initial]
then if the concentration is doubled [A final ]= 2*[A initial] , then
r final = k*[A final ] = 2* k*[A initial] = 2*r initial
then the velocity changes by a factor of 2
b) for a second order reaction in reactant B
r initial = k*[B initial]²
then if the concentration is halved: [B final ]= [B initial]/2 , then
r final = k*[B final ]² = k*( [B initial]/2 )² =k* [B initial]² /4 = r initial /4
then the velocity changes by a factor of 1/4
c) for a second order reaction in reactant C
r initial = k*[C initial]²
then if the concentration is tripled : [C final ]= 3* [C initial] , then
r final = k*[C final ]² = k*( 3*[C initial] )² =k* [C initial]² *9 = 9 * r initial
then the velocity changes by a factor of 9
