The crushed silicon weighing 5.6 grams was burned. Determine: the mass of the formed silicon oxide.

Let’s find the amount of silicon substance Si.

M (Si) = 28g / mol.

n = 5.6g: 28 g / mol = 0.2 mol.

Let’s compose the reaction equation, find the quantitative ratios of substances.

Si + O2 = SiO2

For 1 mole of Si, there is 1 mole of SiO2. Substances are in quantitative ratios

1: 1. The amount of substance is equal.

n (Si) = n (SiO2) = 0.2 mol.

Let’s find the mass of SiO2.

M (SiO2) = 60 g / mol.

m = n × M.

m = 60g / mol × 0.2 mol = 12 g.

Answer: 12 g.