1. The problem statement, all variables and given/known data A sample of helium behaves as an ideal gas as it heated at a constant pressure from 273k to 373 k. If 20.0 J of work is done by the gas during this process, what is mass of helium present? 2. Relevant equations I was thinking about pv=nRt, but not sure. 3. The attempt at a solution Ti= 273k, Tf= 373K, Q=20.0J, P=1atm, m=? Ugghh, how do I solve this? Anyone?