Question

Magnesium burns in air to give magnesium oxide as shown below. If 8g of magnesium oxide product is produced, calculate how much magnesium metal must have been used. You will need some of the data below.

Answer 1

Mass = 4.8 g

Step-by-step explanation:

Given data:

Mass of magnesium oxide produced = 8 g

Mass of magnesium metal burn = ?

Solution:

Chemical equation:

2Mg + O₂ → 2MgO

Moles of MgO:

Number of moles = mass/molar mass

Number of moles = 8 g/ 40.3 g/mol

Number of moles = 0.2 mol

Now we will compare the moles of MgO with Mg.

Mg : MgO

2 : 2

0.2 : 0.2

Mass of Mg:

Number of moles = mass/molar mass

Mass = Number of moles × molar mass

Mass = 0.2 mol × 24 g/mol

Mass = 4.8 g