Which statements below are always true regarding the addition of a catalyst to a reaction:

Question

Which statements below are always true regarding the addition of a catalyst to a reaction:

I. the catalyst is in the same state as the reactants

II. the catalyst lowers the activation energy in a reaction

III. the catalyst raises the value for the rate constant, k

Answer 1

Catalysts only effect the kinetics of the reaction which means they effect rate of reaction by lowering activation energy. Rate is amount of change in time. The value of your rate constant can be calculated by Arrhenius equation K=Ae^-Ea/RT . K is the rate constant , R ideal gas constant, T temperature in kelvin and Ea activation energy , A frequency factor.

Catalyst lowers activation energy Ea ( Correct B) and if you lower Ea value the exponent in would be smaller but be careful there is a negative sign in your ratio (-Ea/RT) which makes the exponent less negative and closer to zero (more positive value for K) which means the rate constant actually increases.(Correct C).

The state of reactant and catalyst do not have to be the same (False A)

Answer 2

I. the catalyst is in the same state as the reactants - FALSE (there are heterogeneous catalysts)

II. the catalyst lowers the activation energy in a reaction - TRUE

III. the catalyst raises the value for the rate constant, k - FALSE