An experimental data on the reaction of H2 and PO3-3 is given below

Question

Initial[PO₃] [Initial H₂] Initial Rate

Experiment 1 0.100 0.100 1.50

Experiment 2 0.200 0.100 3.00

Experiment 3 0.100 0.200 6.00

What is the order of reaction with respect to [PO₃^-3]?

What is the order of reaction with respect to [H²]?

What is the overall reaction?

Answer 1

Look at Experiments where you change one concentration: and compare the rate ratio with the concentration ratio for data that changes only one variable. If they are equal, than the reaction rate order is 1, if the ratio is quadratic, it's 2, and so on.

PO₃^- conc. E2/E1 .2/.1 = 2 rxn rate: E2/E1 3/1.5 = 2 1st order in PO₃^-

[H₂] conc E3/E1 .2/.1 = 2 rxn rate E3/E1 6/1.5 = 4 2nd order in H₂

r = k[PO₃^-][H₂]²