[joules]

I have been provided with the volume of the calorimeter: (240 ml), the maximum fill (pure oxygen and ambient air): 45 atm, maximum temperature: 301.15 K and the volume of the water bath (2 L). 

I have been also provided the amount of heat released and must determine the maximum pressure the calorimeter can handle.

what I have determined so far:

- delta U = q calorimeter = - 10000 J
- the chemical reaction, delta moles = +10.5

Not sure that I need this but calculated it anyways: Heat capacity of the water = 8360 J/K

If this was an ideal gas, max pressure would be calculated by P=nRT/V

So, am I correct that the V = .240 L, R is the gas constant, n = 10.5 and therefore I just need to figure out what T is to solve for pressure?

Ideas that I have to solve for T is:

q = qcalorimeter + qwater
where qcalorimeter = heat capacity of the calorimeter x delta T and Qwater = heat capicity of the water x delta T
but this seems complicated.

Also, I know what delta H is for this reaction as STP.  Would the right approach be to solve for Tcalorimeter using:
delta H = delta U + RT delta n (gas)

Thank you for any assistance provided.