1. The problem statement, all variables and given/known data The question is : Calculate the work done in joules when 1.0 mole of N2H4 decomposed against a pressure of 1.0 atm at 300 K for the equation: 3N2H4 (l)→4NH3(g)+2N2(g) 2. Relevant equations None 3. The attempt at a solution I did it like as: Assuming 100% dissociation of N2H4 4/3 moles of NH3 and 2/3 moles of N2 will be formed. That means a total of 2 moles of gas will be formed , which will have a volume of 2×22.4L at STP. (SINCE AT STP VOLUME OF 1 MOLE OF GAS=22.4L) Which will be equal to 44.8 ×10-3 m3 So work done =PΔV=105×44.8×10-3=4480J (with a negative sign) But its answer is -4988.4 J which is much different from mine. What I think is that mere approximations in the values of Molar volume at STP and pressure change from atm to N/m2 cannot cause such a large deviation. So is my method incorrect? Or the given answer?