The delta H of -484 kJ is the heat given off when 2 moles of H2 react with 1 mole of O2 to make 2 moles of H2O. You don't have anywhere near that much reactants, only 1/4 as much
actual delta H = 0.34 moles H2 x (-484 kJ / 2 moles H2) = 823 kJ
delta E = delta H - PdeltaV = 823 kJ - 0.41 kJ = 822 kJ
