Stoichiometry: Calculating Mass of Magnesium Oxide and Unused Oxygen

What is the result when 24g of magnesium reacts with 32g of Oxygen?

A. 40g of magnesium oxide formed and 16g of oxygen left unused

Answer:

When 24g of magnesium reacts with 32g of oxygen, 40g of magnesium oxide is formed and 16g of oxygen is left unused.

Stoichiometry is a branch of chemistry that deals with the quantitative relationships and calculations of reactants and products in chemical reactions. In this scenario, we are looking at the reaction between magnesium and oxygen.

The balanced chemical equation for the reaction between magnesium and oxygen is: 2Mg + O2 => 2MgO. From this equation, we can see that 2 moles of magnesium react with 1 mole of oxygen to form 2 moles of magnesium oxide.

To calculate the mass of magnesium oxide formed when 24g of magnesium reacts with 32g of oxygen, we first need to determine the molar mass of magnesium (about 24g/mol) and oxygen (about 32g/mol).

Given that 24g of magnesium reacts with 32g of oxygen, there is an excess of oxygen in this scenario. This means that only half of the oxygen will react with the magnesium. So, the mass of magnesium oxide formed will be 24g (from magnesium) + 16g (half of the oxygen) = 40g.

Furthermore, the weight of unused oxygen can be calculated by subtracting the weight of oxygen that reacted from the initial weight of oxygen. Therefore, 32g (initial oxygen) - 16g (oxygen reacted) = 16g of oxygen left unused.

Understanding stoichiometry and being able to perform these calculations is essential in chemistry to predict the outcomes of chemical reactions accurately.