[sosippus]

Hello guys!

I'm having some troubles solving this question. Take this reaction as an example

A + B -> C + D


I have the second order rate constant: k = 0.1 M^(-1) s^(-1). Also have the partial pressure of B: pB = 720 torr.

How can i find the pseudo-first order rate constant for this reaction? Can someone help me please?


--
Here's what I tried:

Convert pB (in torr) to molar fraction of B, through Henry's Law: 722/(3.3*10^7)=0.000023. 
Multiply this value by the second order rate constant: 0.000023*0.1 = 2.3*10^(-6)
Yet, i should have obtained 1.8*10^-4.
--


Can someone please help me? Thanks