4.8 magnesium burned out. How many grams of magnesium oxide was formed.

Let’s write the reaction equation:

2Mg + O2 (t) = 2MgO

Let’s find the amount of magnesium substance:

v (Mg) = m (Mg) / M (Mg) = 4.8 / 24 = 0.2 (mol).

According to the reaction equation, from 2 moles of Mg, 2 moles of MgO are formed, therefore:

v (MgO) = v (Mg) = 0.2 (mol).

Thus, the mass of the formed magnesium oxide:

m (MgO) = v (MgO) * M (MgO) = 0.2 * 40 = 8 (g).

Answer: 8 g.