If 11.87 grams of sand (SiO2) were contained in the mixture, how many atoms of oxygen were in the mixture?

2.38x10²³ atoms oxygen

Explanation:

To solve this question we need to convert the mass of sand to moles using its molar mass (Molar mass SiO₂ = 60.08g/mol). Twice these moles are the moles of Oxygen and using Avogadro's number we can find the amount of atoms of Oxygen in the mixture:

Moles SiO₂:

11.87g * (1mol / 60.08g) = 0.1976moles SiO₂

Moles Oxygen:

0.1976moles SiO₂* 2 = 0.3951moles oxygen

Atoms oxygen:

0.3951moles oxygen * (6.022x10²³atoms / 1mol O₂) =