Magnesium metal burns in oxygen to form magnesium oxide, MgO. (b) How many grams of oxygen are needed to react with 25.0 g of Mg? How many grams of MgO will result?

Verified step by step guidance

1. Step 1: Write down the balanced chemical equation for the reaction. The reaction of magnesium with oxygen to form magnesium oxide is represented as: 2Mg + O2 -> 2MgO
2. Step 2: Calculate the molar mass of Mg and O2. The molar mass of Mg is approximately 24.31 g/mol and the molar mass of O2 is approximately 32.00 g/mol.
3. Step 3: Convert the given mass of Mg (25.0 g) to moles using its molar mass. The formula to convert grams to moles is: moles = mass (g) / molar mass (g/mol).
4. Step 4: Use the stoichiometry of the reaction to find the moles of O2 needed. From the balanced chemical equation, you can see that the ratio of Mg to O2 is 2:1. Therefore, the moles of O2 needed is half the moles of Mg.
5. Step 5: Convert the moles of O2 needed to grams using its molar mass. The formula to convert moles to grams is: mass (g) = moles * molar mass (g/mol).
6. Step 6: To find the mass of MgO produced, use the stoichiometry of the reaction. From the balanced chemical equation, you can see that the ratio of Mg to MgO is 1:1. Therefore, the moles of MgO produced is equal to the moles of Mg. Convert this to grams using the molar mass of MgO.

Key Concepts

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows us to calculate the amounts of substances consumed and produced in a reaction based on balanced chemical equations. Understanding stoichiometry is essential for determining how much oxygen is needed to react with a given mass of magnesium and how much magnesium oxide will be produced.

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is crucial for converting between the mass of a substance and the number of moles, which is necessary for stoichiometric calculations. For magnesium (Mg) and oxygen (O2), knowing their molar masses allows us to determine how many grams of each are involved in the reaction.

Balanced Chemical Equation

A balanced chemical equation represents a chemical reaction with equal numbers of each type of atom on both sides of the equation. For the reaction of magnesium with oxygen, the balanced equation is 2Mg + O2 → 2MgO. This equation is fundamental for stoichiometric calculations, as it provides the mole ratios needed to determine the amounts of reactants and products involved in the reaction.