Heat, Internal Energy, & Work?

Question

A bottle containing an ideal gas has a volume of 2 m^3 and a pressure of 1x10^5 N/m^2 at a temperature of 300K. The bottle is placed against a metal block that is maintained at 900K and the gas expands as the pressure remains constant until the temperature of the gas reaches 900K. The change in internal energy of the gas is 6x10^5J. HOw much heat did the gas absorb?

Answer 1

In expanding from 2m^3 at a constant pressure P of 10^5N/m^2 from 300K to 900K the gas would triple its volume V from 2 to 6 m^3 and perform the following amount of work :

P x deltaV = W = 4 x 10^5 J

Its internal energy increased by 6 x10^5 J  so the heat source had to supply (and the gas had to absorb) heat to provide both for the expansion work and for the increase in internal energy:

(6 + 4) x 10^5 J =10^6J

Answer 2

ask the chemists.