Question

How many grams of magnesium metal will react completely with 6.3 liters of 4.5 M HCl? Show all of the work needed to solve this problem. Mg (s) + 2HCl (aq) yields MgCl2 (aq) + H2 (g)

Answer 1

The reaction is: Mg + 2HCl -----> MgCl2 + H2 

M = mol / L 
mol = M x L = 4.5 mol/L x 6.3 L = 28.4 mol HCl 
1 mol Mg reacts with 2 mol HCl 
28.4 mol HCl x (1 mol Mg / 2 mol HCl) = 14.2 mol Mg 
Molar mass of Mg is 24.3 g/mol. 
14.2 mol Mg x (24.3 g / 1 mol) = 344 g Mg