A 7 L container holds 7 mol and 18 mol of gasses A and B, respectively. Every three of molecules of gas B bind to one molecule of gas A and the reaction changes the temperature from 320^oK to 330 ^oK. By how much does the pressure change?

1 Answer
Oct 14, 2017

Pressure changes directly with amount of matter and with temperature. We'll do this in two steps.

Explanation:

If the reaction is of the form A+3B->C where C=AB_3:

(1)
In the reaction 18 mol of B will bind to 6 mol of A to form 6 mol of C (assuming C is also a gas!).
1 mol of A will be left. So now we have 7 mol in stead of 25 mol.
p_1=p_0 xx7/25

(2)
Temperature goes from 320 K to 330 K:
p_(end)=p_1 xx330/320

Total change:
p_(end)=p_0xx7/25xx330/320~~0.29xxp_0

Note:
More likely the reaction is of the form:
A_2+3B_2->2C where C=AB_3

In this case the number of moles goes from:
7A+18B to 1A+12C
And the fraction in step (1) will be 13/25