With the increasing concerns about global warming and smog pollution, scientists have been looking at other sources of energy. One of these sources is hydrogen gas. Unfortunately, hydrogen gas is more difficult to store than liquids and solids. Calculate the volume of hydrogen, at 20°C and 101.325 kPa, that is needed to produce the same amount of energy as the combustion of 1 L of octane, C8H18. The density of octane is 0.7025 g/mL, and ΔH°f of octane is −249.9 kJ/mol.