What is w when 1.27 kg of H2O(l), initially at 25.0oC, is converted into water vapour at 133oC against a constant external pressure of 1.00 atm? Assume that the vapour behaves ideally and that the density of liquid water is 1.00 g/mL. (Remember to include a "+" or "-" sign as appropriate.)

Answer 1

I think I've answered this before.
H2O(l) ==> H2O(steam)
Convert kg to mols H2O at 25 and calculate the volume occupied. Do the same for volume at 133 C using PV = nRT.
w = -p*delta V.