Calculate the experimental molar volume (l/mol) for an ideal gas at stp using the information that follows. a 15.0 mg piece of solid magnesium was reacted completely with hydrochloric acid in a reaction flask with a volume of 135 ml. the temperature of the reaction was 22.3 °c and the pressure of the gas produced by the reaction was 11.3 kpa. calculate the volume of hydrogen gas that would have formed in this reaction had it been conducted under standard temperature and pressure conditions (use the combined gas law). use the volume you have just determined, along with the number of moles of hydrogen gas that would have formed from 15.0 mg of magnesium reactant, to calculate the molar volume of this gas at stp