Question

After 5 minutes, 1.98x10^-23 moles of hydrogen gas is produced. How many grams of magnesium reacted?

Answer 1

Answer:

$\large \boxed{4.81 \times 10^{-22} \text{ g Mg}}$

Explanation:

We will need a balanced equation with masses, moles, and molar masses, so let’s gather all the information in one place.

Mᵣ:         24.30

                Mg + 2H⁺ ⟶ Mg²⁺  +  H₂  

n/mol:                                      1.98 × 10⁻²³

1. Calculate the moles of Mg

The molar ratio is 1 mol Mg:1 mol H₂

$\rm \text{Moles of Mg} =1.98 \times 10^{-23} \text{ mol H}_{2} \times \dfrac{\text{1 mol Mg}}{\text{1 mol H}_{2}} = 1.98 \times 10^{-23} \text{ mol Mg}$

2. Calculate the mass of Mg

$\text{Mass of Mg} = 1.98 \times 10^{-23} \text{ mol Mg} \times \dfrac{\text{24.30 g Mg}}{\text{1 mol Mg}} = \mathbf{4.81 \times 10^{-22}} \textbf{ g Mg}\\\\\text{The mass of Mg reacted is \large \boxed{\mathbf{4.81 \times 10^{\mathbf{-22}} \textbf{ g Mg}}} }$