Hi

Lets expand that equation: Delta H = q - P(surr) Delta V + P (sys) Delta V. So instead of U i put q + w and w in this case is -P(surr) delta V. One important thing you need to pay attention to is that the sign of work on the surrounding is the opposite of the sign of work that is done on the system this is why one of the P delta V is negative and the other one is positive. So if the system is doing work on the surrounding the work done by the system is negative and the work done on the surrounding is positive etc. Now there are two cases where Delta H = q --> 1) when in a chemical reaction you go from liquid to solid or vice versa the volume does not change by much so Delta V can be assumed to be 0 therefore Delta H = q. 2) If pressure of the surrounding is equal to the pressure of the system (i.e. Psurr = Psys) then the two P delta V expressions cancel out and Delta H = q. In most of the MCAT questions Delta H = q and therefore for question 413 we know that delta G = delta H + T delta S and since delta H = q then this signifies a non-PV work.

Hope this helps.