posted by Stephanie .
Calculate the volume of gas you would expect to be evoleved if X mol of magnesium were reacted with an excess of HCl at standard conditions. Would the answer be X, 22.4X, or 22400X?
X what? 22.4X what? 22,400X what?
Mg + 2HCl ==> MgCl2 + H2
X mol Mg will produce X mol H2. 1 mol occupies 22.4L at STP; therefore, X mols will occupy 22.4X L at STP. So you could have two of the correct answers above if 22.4X is L and 22,400X is mL.