kinetics summary

Question

P and Q react to form E. In one experiment, the concentration of P is tripled while Q is kept constant. This causes the rate to triple. In a second experiment, the concentration of Q is doubled while the concentration of P is kept constant. The rate quadruples. Write a rate equation for this reaction and determine the overall order of the reaction.

Answer 1

If [P] is tripled and [Q] is constant and the rate also triples, this means the reaction is FIRST order in P.

When you double [Q] and keep [P] constant and the rate quadruples, this means the reaction is SECOND order in Q.

The rate equation would be ...

Rate = k[P]¹[Q]² or simply Rate = k[P][Q]²

Overall order is THIRD order (you add the exponents; 1 + 2 = 3)