After 5 minutes, 1.98 * 10-3 moles of hydrogen gas is produced. How many grams of magnesium reacted?

0.048 g

Explanation:

We are given;

Moles of hydrogen gas as 1.98 * 10^-3 moles

We are required to calculate the mass of Magnesium that reacted

Assuming the equation for the reaction is;

Mg + 2HCl → MgCl₂ + H₂

From the reaction;

1 mole of magnesium reacts with 2 moles of HCl to produce 1 mole of MgCl₂ and 1 mole of hydrogen gas

Therefore;

Mole ratio of Mg : H₂ is 1 : 1

Thus, moles of Mg = Moles of H₂

Moles of Mg is 1.98 * 10^-3 moles

But, molar mass of Mg = 24.305 g/mol

Therefore;

Mass of Mg = 1.98 * 10^-3 moles * 24.305 g/mol

= 0.048 g

The mass of Mg that reacted is 0.048 g