Question

Determining reaction order: the method of initial rates

2C+3D----> E+F

exp	(c)	(d)	Rate (m/s)
1	2	2	10.00
2	6	2	30.00
3	1	1	1.25
4	2	4	80.00

Determine the order with respect to c and d and calculate the value of k

THe answer is

ANswer: Rate=k(c)^1(D)^3                  K=0.675s^-1M-3

But how do you show the work

Answer 1

From data 1 & 2 when conc of d (2) is kept constant and conc of c is trippeled ( 2 to 6) the rate of reaction is also trippled ( 10 to 30).This shows that rate of reaction varies directly as first power of conc. Hence the order of reaction wrt c is 1.

Similarlly From data 3 & 4 when conc of d is deccreases & then increasest thhen the rate of reaction is also increases & decreases accordingly.Hence the order of reaction wrt d is 3

K = r ( rate of reaction) / [c] [d]³

= 0.1 / [2] [8] = 0.1 / 16 = 0.625 x 10^-3 M^-1 .