The reaction between zinc and hydrogen gas is:
Zn + H₂ → ZnH₂
So for every 1 mole of H₂ gas, it needs 1 mole of Zinc. The atomic weight of H2₂ is 2 g/mol, and Zinc is 67.425 g/mol. The density of H₂ at atmospheric pressure and at 293 K is 0.00016 g/mL. The solution is as follows:
Mass = Density*Volume = (0.00016 g/mL)(150 mL) = 0.024 g H₂
Moles H₂ = 0.024 g H₂ * 1 mol/2 g = 0.012 mol H₂
Thus, it also needs 0.012 mol Zn.
Mass of Zn needed = 0.012 mol * 67.425 g/mol = 0.8091 g Zn
