Determine the volume and number of oxygen molecules required to obtain 12 g of magnesium oxide.

The combustion reaction of magnesium is described by the following chemical reaction equation:

2Mg + O2 = 2MgO;

To obtain two moles of magnesium oxide, one mole of oxygen is required.

Let’s determine the amount of substance in 12 grams of magnesium oxide.

M MgO = 24 + 16 = 40 grams / mol;

N MgO = 12/40 = 0.3 mol;

Let us determine the volume (n.v.) and the number of oxygen molecules.

N O2 = N MgO / 2 = 0.3 / 2 = 0.15 mol;

One mole of ideal gas under normal conditions takes a volume of 22.4 liters.

The oxygen volume will be:

V O2 = 0.15 x 22.4 = 3.36 liters;

One mole contains 6.022 x 10 ^ 23 molecules.

The number of oxygen molecules will be:

K O2 = 0.15 x 6.022 x 10 ^ 23 = 9.033 x 10 ^ 22 molecules;