3.5 cm of Mg ribbon(0.009729 g/cm0 reacts with HCL to produce 32.6 ml. of Hydrogengas at 750 mm Hg and 20 degree C. the vapor pressure of water at 20 degree C is 17.5 mm Hg. Calculate the molar volume of hydrogen (L/mole) and the percent error in your determination

See your post above.