Thermodynamics pressure reaction question

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In the reaction where 2.00 mol of SO2 reacts completely with O2 at a constant pressure of 101 kPa, the only product remaining is SO3 at 25 degrees Celsius, with 198 kJ of energy released as heat. The heat transfer (q) is equal to the change in enthalpy (deltaH), which is -198 kJ due to the constant pressure condition. To calculate the change in internal energy (deltaU), the relationship deltaH = deltaU + delta(PV) is used, where delta(PV) is expressed as RTdelta(n). The assumption of constant temperature at 25 degrees Celsius is crucial for these calculations, as it simplifies the analysis of the thermodynamic properties involved. The process does not need to be adiabatic, allowing for heat exchange with the surroundings.
thatoneguy6531
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So the question is: When 2.00 mol of SO2 reacts completely with 02 in a constant pressure reactor, the only material left in the reactor once the reaction has stopped is SO3 at 25 degrees celsius. The constant pressure in the reactor was 101kPa and 198 kJ of energy is released as heat. Assume Psys=Pext throughout the process. Calculate deltaH, deltaU, q and w per mole of O2 consumed for this reaction.

So I know q = deltaH = -198kJ since its a constant pressure process and I know to solve for deltaU I use:
deltaH = delta U + delta(PV) and in the solution apparently the delta(PV) = RTdelta(n). What I don't understand is why the temperature is assumed to be constant at 25 degrees celsius.
 
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thatoneguy6531 said:
What I don't understand is why the temperature is assumed to be constant at 25 degrees celsius.

Process doesn't have to adiabatic.
 

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