I have the right answers but dont how to work itout. An ideal gas initially at 4

Question

I have the right answers but dont how to work itout.
An ideal gas initially at 408 Kis compressed at a constant pressure of 34 N/m2 from a volume of 3.0m3 to a volume of 1.8 m3. In the process, 75J of heat is lost by the gas. (a) What is the change in internal energy ofthe gas?
-34.2 J
(b) What is the final temperature of the gas?
245 K I have the right answers but dont how to work itout.
An ideal gas initially at 408 Kis compressed at a constant pressure of 34 N/m2 from a volume of 3.0m3 to a volume of 1.8 m3. In the process, 75J of heat is lost by the gas. (a) What is the change in internal energy ofthe gas?
-34.2 J
(b) What is the final temperature of the gas?
245 K

Explanation / Answer

.    dQ = 75 J .    dW = P * dV = 34 * ( 3 - 1.8 ) = 40.8 .      From First law of thermodynamics : .      dQ = dU + dW    .    ==> dU = dQ - dW = 75 - 40.8 = 34.2 J . As the work is done on the gas : dU = -34.2 J . (b) At constant Pressure : Volume isdirectly proportional to Temp .         Hence V1 / T1 = V2 /T2 .       ==> T2    = ( V2 * T1 ) / V1 = (1.8 *408 ) / 3 = 244.8 = 245 K . Hope this helps u!

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