A sample of 35.0 g of magnesium (Mg) undergoes complete oxidation according to the reaction: 2 Mg + O_2 → 2 MgO. What mass of magnesium oxide (MgO) is produced?

• A. 58.0 g
• B. 70.0 g
• C. 35.0 g
• D. 29.2 g

Answer: (A)

Verified step by step guidance

1. Write the balanced chemical equation for the reaction: 2 Mg + O_2 \rightarrow 2 MgO.
2. Calculate the molar mass of magnesium (Mg) and magnesium oxide (MgO). Use the atomic masses: Mg = 24.3 g/mol, O = 16.0 g/mol, so MgO = 24.3 + 16.0 = 40.3 g/mol.
3. Convert the given mass of magnesium (35.0 g) to moles using the formula: \(\text{moles Mg} = \frac{\text{mass Mg}}{\text{molar mass Mg}}\).
4. Use the stoichiometric ratio from the balanced equation to find moles of MgO produced. Since 2 moles of Mg produce 2 moles of MgO, the moles of MgO produced are equal to the moles of Mg reacted.
5. Convert the moles of MgO to mass using the formula: \(\text{mass MgO} = \text{moles MgO} \times \text{molar mass MgO}\). This will give the mass of magnesium oxide produced.