How much air will it take to burn 36 g of magnesium?

m (Mg) = 36 g.
Let’s determine the volume of air. We write down the solution.
1. Let’s compose the equation of reactions and equalize it.
2Mg + O2 = 2MgO.
2. Find the amount of magnesium substance.
n = m / M.
Where n is the amount of substance.
m is the mass of the substance.
M is the molar mass of the substance.
M (Mg) = 24.3 g / mol.
n (Mg) = 36 / 24.3 = 1.48 mol.
3. Using the reaction equation, we find the amount of air substance.
1.48 mol Мg – x mol О2.
2 mol Мg – 1 mol О2.
X = 1.48 × 1 ÷ 2 = 0.74 mol O2.
4. Find the volume of air.
n = V / Vm.
V = n × Vm = 0.74 mol × 22.4 L / mol = 16.6 L O2.
Answer: the air volume is 16.6 liters.