Determine the mass of magnesium, which requires 67.2 liters of oxygen to burn, conditions are normal.

Let’s execute the solution:
1. In accordance with the condition of the problem, we write the equation:
X g -? V = 67.2 l;
2Mg + O2 = 2MgO – compounds, obtained magnesium oxide;
2. Calculations:
M (Mg) = 24.3 g / mol.
3. Proportions:
1 mol of gas at normal level – 22.4 liters;
X mol (O2) – 67.2 liters. hence, X mol (O2) = 1 * 67.2 / 22.4 = 3 mol;
X mol (Mg) – 3 mol (О2);
-2 mol – 1 mol from here, X mol (Mg) = 2 * 3/1 = 6 mol.
4. Find the mass of the metal Mg:
m (Mg) = Y * M = 6 * 24.3 = 145.8 g.
Answer: the process will require 145.8 g of magnesium.