Question

Calculate how much oxygen (in grams) required to combust 10 moles of magnesium from the given equation: $2Mg + {O_2} \to 2MgO$

Answer 1

Look at the stoichiometry of the reaction. Here, 2 moles of Mg requires 1 mole of ${O_2}$. Hence, 1 mole of Mg requires 0.5 moles of ${O_2}$. Now, calculate the number of moles of ${O_2}$ required for the combustion of 10 moles of Mg. 1 mole of ${O_2}$ weighs 32g. The molar mass of Mg is 24g/mol.

Complete step by step answer:
In the given reaction, magnesium undergoes oxidation by oxygen to form Magnesium dioxide. It is a combustion reaction.
$2Mg + {O_2} \to 2MgO$
A combustion reaction is a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat.
Before understanding how to calculate the amount of ${O_2}$ required for the reaction, let us analyze the information available from the balanced chemical equation.
Here, the reactants are magnesium and oxygen. The product formed is magnesium oxide.
The coefficients 2 for Mg and MgO are the stoichiometric coefficients. They represent the number of moles (or molecules) taking part in the reaction or formed in the reaction.
According to the given chemical reaction,
One mole of ${O_2}$ reacts with 2 moles of Mg to give 2 moles of MgO.
Therefore, 1 mole of Mg requires 0.5 moles of ${O_2}$.
Now, we need to calculate the number of moles of ${O_2}$ required to react with 10 moles of Mg.
The number of moles of ${O_2}$ required to react with 10 moles of Mg = 10 $\times$ 0.5 = 5 moles.
We are asked to find the amount of oxygen in grams.
We know that 1 mole of oxygen gas weighs 32 g. Therefore, 5 moles weigh 5 $\times$ 32 = 160g.

The answer is: 160g of ${O_2}$ is required for the combustion of 10 moles of Mg.

Note: Ensure that the given reaction is balanced. According to the law of conservation of mass, a balanced chemical equation has the same number of atoms of each element on both sides of the equation.
-1 mole of ${O_2}$ is equal to 22.4L. This applies to all gases.
-Remember to use the molecular mass (in grams) of oxygen and not the atomic weight. The atomic weight of oxygen is 16g/mol while the molecular mass of oxygen is 32g/mol.