Question

A 2.5 mg sample of magnesium powder is ignited with 2 mg oxygen in a sealed container. All of the magnesium is consumed and 4.15 mg of white solid magnesium oxide is formed .

Find the mass of the unreacted oxygen

Answer 1

Total mass of the reactant = 2+2.5 =4.5 mg

Total mass of product = 4.15 mg

therefore, mass of unreacted oxygen = 4.50-4.15 = 0.35 g