Question

Consider the following reaction:2 HCl(aq) + Mg(s) → MgCl2(aq) + H2(g)-If you have 18.82 g of Mg what volume (liters) of 1.0M HCI will you need to fully dissolve the Mg?

Answer 1

Volume of HCl (V) = 1.55 L

Step-by-step explanation

Given:

Mass of Mg = 18.82 g

Concentration of HCl = 1.0 M

Required: Volume of HCl

Solution

Step 1: Calculate the number of moles of Mg

n = m/M where n is the moles, m is the mass and M is the molar mass

n = 18.82g/24,305g/mol

n = 0.774 mol

Step 2: Use the stoichiometry to calculate the moles of HCl, the reaction is already balanced.

The molar ratio between HCl and Mg is 2:1

Therefore the moles of HCl = 0.774 mol x (2/1) = 1.55 mol

Step 3: Calculate the volume of HCl

C = n/V where C is the concentration, n is the moles and V is the volume

Re-arrange to get V

V = n/C

V = 1.55 mol/1.0 mol.L^-1

V = 1.55 L