Calculate the mass of magnesium oxide that is produced by burning 24 grams of magnesium.

Given:

m (Mg) = 24 g;

To find:

m (MgO) -?

Decision:

1) We compose the reaction equation corresponding to the condition of the given problem:

2Mg + O2 = 2MgO;

2) Find the amount of magnesium contained in 24 grams of metal:

n (Mg) = m: M = 24 g: 24 g / mol = 1 mol;

3) We compose logical equality:

if 2 mol Mg gives 2 mol MgO,

then 1 mole of Mg will give x mole of MgO,

then x = 0.5 mol.

4) Find the mass of magnesium oxide formed during the reaction:

m (MgO) = n * M = 0.5 mol * 40 g / mol = 20 g.

Answer: m (MgO) = 20 g.