Magnesium metal burns in oxygen to form magnesium oxide, MgO. (c) How many grams of Mg are needed to react with 25.0 g of O2? How many grams of MgO will result?

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Step 1: Write down the balanced chemical equation for the reaction. The balanced equation for the reaction of magnesium with oxygen is 2Mg + O2 -> 2MgO. This tells us that 2 moles of Mg react with 1 mole of O2 to form 2 moles of MgO.

Step 2: Convert the given mass of O2 to moles. You can do this by dividing the mass of O2 by its molar mass. The molar mass of O2 is approximately 32.00 g/mol.

Step 3: Use the stoichiometry of the reaction to find the moles of Mg needed. From the balanced equation, we know that 2 moles of Mg are needed for every 1 mole of O2. So, multiply the moles of O2 by 2 to find the moles of Mg needed.

Step 4: Convert the moles of Mg to grams. You can do this by multiplying the moles of Mg by its molar mass. The molar mass of Mg is approximately 24.31 g/mol.

Step 5: To find the mass of MgO that will be produced, use the stoichiometry of the reaction again. From the balanced equation, we know that 2 moles of MgO are produced for every 2 moles of Mg that react. So, the moles of MgO produced will be the same as the moles of Mg that reacted. Convert this to grams by multiplying by the molar mass of MgO, which is approximately 40.31 g/mol.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

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 magnesium reacts with a given mass of oxygen.

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 are needed for 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 to form magnesium oxide (Mg + O2 → MgO), balancing the equation ensures that the law of conservation of mass is upheld. This balance is essential for accurately calculating the amounts of reactants and products involved in the reaction.

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Textbook Question

Magnesium metal burns in oxygen to form magnesium oxide, MgO. (a) Write a balanced equation for the reaction.

Textbook Question

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?

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