100mg magnesium reacts with 20ml of 1.0m hcl

1 answer · Chemistry 

Answer

Mg + 2 HCl = MgCl2 + H2 

(100.00 x 10^-3 g Mg) / (24.30506 g Mg/mol) = 0.0041143696 mol Mg 
(0.02000 L) x (1.0 mol/L HCl) = 0.02000 mol HCl 

0.0041143696 mole of Mg would react completely with 0.0041143696 x (2/1) = 0.0082287392 mole of HCl, but there is more HCl present than that, so HCl is in excess and Mg is the limiting reactant, 

(0.0041143696 mol Mg) x (1 mol H2 / 1 mol Mg) = 0.0041144 mol H2 = 4.1144 millimoles H2

The answer to this problem is. 67