chem
posted by Yuni .
The reaction AB(aq)>A(g)+ B(g)is second order in AB and has a rate constant of 0.0282 M^{1} s^{1} at 25 Celsius. A reaction vessel initially contains 250 mL of 0.105 M AB which is allowed to react to form the gaseous product. The product is collected over water at 25 Celsius.
1How much time is required to produce 115.0 mL of the products at a barometric pressure of 779.9 mmHg. (The vapor pressure of water at this temperature is 23.8 mmHg.)

I would do this.
Use P = MRT
where P: = (779.923.8)/760
and solve for M which should give A and B concns (I assume 0.115L is the volume of the gases).
Take 1/2 that to find M needed for AB and apply the second order equation of
1/A  !/Ao = akt
You know Ao, a = 1, you know k and A (from the calculation). Solve for t which should be i s since k is in s. 
is the answer 1392 s?