Question

# Consider the reaction A+2B⇌C whose rate at 25 ∘C was measured using three different sets of...

Consider the reaction

A+2B⇌C

whose rate at 25 ∘C was measured using three different sets of initial concentrations as listed in the following table:

 Trial [A] (M) [B] (M) Rate (M/s) 1 0.15 0.010 2.7×10−4 2 0.15 0.020 5.4×10−4 3 0.30 0.010 1.1×10−3

Calculate the initial rate for the formation of C at 25 ∘C, if [A]=0.50M and [B]=0.075M.

Express your answer to two significant figures and include the appropriate units.

see experiment 1 and 3:

[A] doubles

[B] is constant

rate becomes 4 times

so, order of A is 2

see experiment 1 and 2:

[A] is constant

[B] doubles

rate doubles

so, order of B is 1

overall order = 2 + 1 = 3

Rate law is:

rate = k*[A]^2*[B]

Put values from 1st row of table in rate law

rate = k*[A]^2*[B]

2.7*10^-4 = k*0.15^2*0.01^1

k = 1.2 M-2.s-1

Now put all values to find rate at given concentration

rate = k*[A]^2*[B]

rate =1.2*0.5^2*0.075

rate = 0.0225 M/s