A #3 L# container holds #9 # mol and #12 # mol of gasses A and B, respectively. Groups of three of molecules of gas B bind to two molecules of gas A and the reaction changes the temperature from #160# #K# to #360# #K#. How much does the pressure change?
1 Answer
The pressure will be reduced by the chemical reaction but increased by the temperature change. The reaction prevails, so the final pressure is approximately
Explanation:
We need to assume that A and B are monatomic initially, because we are not told.
The balanced equation will be:
Gas B will be the limiting reagent, since the reaction requires
That means all
The volume does not change, so there are two steps in considering the change in pressure:

We have gone from
#21# #mol# of gas to#5# #mol# of gas in the same volume, to the pressure will be#5/21# of its initial value. 
The temperature has changed from
#160# #K# to#360# #K# , which means the pressure will be#360/160# of the initial value.
Combining these two things, the final pressure will be