Chemistry Prof. Assasingham question! Consider the reaction H2(g)+Cl2(g)->2HCl(g)?

Delta E is going to equal delta H (times 3) because delta V is 0. There are 2 moles of reactants and 2 moles of products, so 2 - 2 = 0. Px0 = 0 so that part of the equation drops out. Its times 3 because delta H is expressed per 1 mole and you need 3 for your question.