Doubt with a calculation of the entropy of the surroundings.
If we have an exercise like this:
"Two moles of a perfect diatomic gas evolve from state 1 to state 2 through an irreversible process.
In this process, the gas starts from a molar volume of 0.04 m3 / mol and 100 K to have a temperature of 500 K keeping the pressure of the system constant. This process occurs between 2 heat sources, one of 100 K and another of 500 K.
Determine the entropy variation of the universe "
My problem is that when I do the entropy balance of the surroundings, I do not know what temperature to use for "the surroundings" since I have two heat reservoirs.
[NOTE] I know, this is not so advanced.
