Calculate the mass of magnesium reacted with 0.1 mol of oxygen.

n (O2) = 0.1 mol.

Determine the mass of magnesium reacted with oxygen. We write down the solution.

First, we write down the equation of reactions.

2Mg + O2 = 2MgO

Using the reaction equation, we find the amount of magnesium.

X mol of magnesium – 0.1 mol of oxygen

2 mol magnesium – 1 mol oxygen

Find the unknown value of x.

X = 2 mol * 0.1 mol: 1 mol = 0.2 mol Mg.

Next, we find the mass of magnesium.

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 = n * M = 0.2 * 24 g / mol = 4.8 g of magnesium.

Answer: m (Mg) = 4.8 g.