Calculate the mass of magnesium oxide that can be obtained by completely burning 480 grams of magnesium.

Given:

m (Mg) = 480 g;

To find:

m (MgO) -?

Solution:

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

2Mg + O2 = 2MgO;

2) Find the amount of magnesium contained in 480 grams of metal:

n (Mg) = m: M = 480 g: 24 g / mol = 20 mol;

3) We compose logical equality:

if 2 mol Mg gives 2 mol MgO,

then 20 mol of Mg will give x mol of MgO,

then x = 20 mol.

4) Find the mass of magnesium oxide formed as a result of the reaction:

m (MgO) = n * M = 20 mol * 40 g / mol = 800 g.

Answer: m (MgO) = 800 g.