An introductory chemistry laboratory class was asked to determine the empirical

Question

An introductory chemistry laboratory class was asked to determine the empirical formula of the magnesium oxide that is formed when magnesium reacts with oxygen from the air. Give a brief procedure on how the class can determine the empirical formula of the synthesized magnesium oxide. Considering air composition, what is/are possible side product/s and what can be included in the procedure to maximize the production of the desired product? Write the balanced chemical reaction for the formation of the side product/s.Hint: The major product is water insoluble while the side product is water-soluble.

Explanation / Answer

Solution-

Let’s assume that We heated 0.297 g of magnesium and obtained 0.493 g of the oxide. What is the empirical formula of magnesium oxide?

Empirical formula of a chemical compound is the simplest positive integer ratio of atoms present in compound The ratio of atoms is the same as the ratio of moles.

So our job is to calculate the molar ratio of Mg to O.

Mass of Mg = 0.297 g

Mass of magnesium oxide = mass of Mg + mass of O

0.493 g = 0.297 g + mass of O

Mass of O = (0.493 – 0.297) g = 0.196 g

# Moles of Mg = wt. in g/Mol.wt = 0.297g /24.3g = 0.0122 mol of Mg

# Moles of O = 0.196g /16.0 g = 0.0122 mol of O

To get the integer value divide both the value by 0.0122

Mg = 0.0122/0.0122 = 1

O = 0.0122/0.0122 = 1

Mole of Mg and O are same there is 1 mole of Mg for 1 mol of O

Mole ration is = Mg:O = 1:1

The empirical formula of magnesium oxide is MgO

Answer- Empirical formula of magnesium oxide is MgO

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