Question

One reaction that produces hydrogen gas can be represented by the unbalanced chemical equation
Mg(s) + HCl(aq) −→ MgCl2(aq) + H2(g) .
What mass of HCl is consumed by the reac- tion of 3.72 mol of magnesium?
Answer in units of g.

Answer 1

We will place coefficients in the reaction equation:
Mg(s) + 2HCl(aq) −→ MgCl2(aq) + H2(g) .
According to the reaction equation, at interaction of 1 mol of magnesium with hydrochloric acid 1 mol of hydrogen is formed.
Then at interaction of 3,72 mol of magnesium with hydrochloric acid 3,72 mol of hydrogen are formed.
The molar mass of hydrogen is equal to 2,00 g/mol.
Therefore, at reaction of 3,72 mol of magnesium with hydrochloric acid are formed 3,72∙2,00 =7,44 g of hydrogen

Answer: 7,44 g of hydrogen is consumed