)9.45 g of liquid hexane (C6H14) is introduced into a 10.0 L vessel containing 13.15 atm of oxygen gas at 21ºC and ignited, yielding carbon dioxide and water. If the vessel is then cooled to –10ºC, what will be the gas pressure inside the vessel?

i just found the O2 and Hexane  mole and i didn't know what to do after that