Rate Laws Given the data below for the reaction, 2 A + 2 B + 4 C => D + E + 3 F,

Question

Given the data below for the reaction, 2 A + 2 B + 4 C => D + E + 3 F, 

Experiment	Initial conc of A, mol/L	Initial conc of B, mol/L	Initial conc of C, mol/L	Initial rate, mol/L.s
1	0.1	0.2	0.4	2 x 10-3
2	0.2	0.2	0.4	2 x 10-3
3	0.3	0.4	0.4	8 x 10-3
4	0.4	0.6	0.2	9 x 10-3

Calculate the value of k to 3 significant figures. Do NOT use scientific notation! 

Answer 1

Comparing expts 1&2 ... zero order in A b/c doubling A has no effect on rate

Comparing expts 2&3 ... 2nd order in B b/c doubling B results in a rate increase of 4x

Comparing expts 3&4 ... 1st order in C b/c increasing B by 1.5 times and Reducing C in half changes rate by 1.125 which is expected if rate is directly related to [C], ie is 1st order in C

Rate = k[B]²[C]

Using expt 1:

rate = 0.002 M/s

[B] = 0.2 M

[C] = 0.4 M

k = 0.002 Ms^-1/(0.2 M)²(0.4M)

k = 0.125 M^-2s^-1