How to Calculate the Number of Formula Units in a Given Mass of Alumina (Al₂O₃)?

23 Apr 2023

What is the question related to the data?

How many formula units are in 9.3 g of alumina (Al₂O₃)?

What are the steps to calculate this?

5.5 × 10²² formula units Al₂O₃

In order to calculate the number of formula units in a given mass of alumina (Al₂O₃), you can follow these steps:

Given mass of Al₂O₃ is 9.3 g

Avogadro's Number: 6.022 × 10²³ formula units/mol

Molar Mass of Al: 26.98 g/mol

Molar Mass of O: 16.00 g/mol

Molar Mass of Al₂O₃: 2(26.98) + 3(16.00) = 101.96 g/mol

9.3 g Al₂O₃ x (1 mol Al₂O₃ / 101.96 g Al₂O₃) x (6.022 × 10²³ formula units Al₂O₃ / 1 mol Al₂O₃) = 5.5 × 10²² formula units Al₂O₃

Given data has 2 significant figures, so the final answer is approximately 5.5 × 10²² formula units Al₂O₃