1. The problem statement, all variables and given/known data 2 moles of an ideal gas at 300K and 5 bar is expanded adiabatically at a constant pressure of 1 bar till the volume doubles. Cv = 3R/2. Calculate w, q, dE, dH and change in T. 2. Relevant equations See below 3. The attempt at a solution I found that w = dE = -997.78J I solved dH by: dH = CpdT = -1.66kJ (found Cp by Cp=Cv+nR ; found dT by Cv=dE/dT) I was wondering if we could solve dH another way: dH = dE + d(PV) However, I get a different answer.. dH = dE + Pext dV (because pressure is constant) dH = -997.78J +-997.78J (because Pext dV is work) dH = -2.00 kJ I also tried another way: dH = dE + d(nRT) dH = -977J + (2mol)(8.3145J/K)(-80K) dH = -1.08kJ I am not getting the same value for each of the different ways I am using.... Am I doing something wrong or am I not allowed to solve dH using the other methods? Also, at constant pressure, isn't dH = qrev.. and q=0, so shouldn't dH = 0?