1.4 moles of an ideal gas with Cv = 3R/2, initially confined to a container of volume 9 litre and at a temperature 20 C, expand (or are compressed) against a constant external pressure of 1.1 atm until the final pressure of the gas is equal to the external pressure and the final temperature of the gas is equal to the temperature of the surroundings. During this process the system does 3,680 J of work on the surroundings. Calculate the change in entropy, Delta S, of the gas (in J / K).
I'm kind of thrown off by the T(final) = T(surroundings). I calculated V(final) using w=-p(ex)(dV) and used that to calculate T(final) using the ideal gas law. I get 402.3K which seems weird to me that it would be higher. Am I supposed to put in the 3/2R instead of just R when dividing to solve for T? In that case I get 268.2K. After getting the T(final) can I just plug all the data into deltaS = nCvln(Tf/Ti) + nRln(Vf/Vi)? Thanks, and no rush.. just need some clarification. Any tips for solving problems of this sort?