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Multiple Choice
Consider the following reaction: 2 Mg + O2 → 2 MgO. What mass (g) of MgO can be created from 4.3 g of O2 and excess Mg?
A
9.5 g
B
8.6 g
C
10.8 g
D
12.4 g
Verified step by step guidance
1
Start by identifying the balanced chemical equation: 2 Mg + O2 → 2 MgO. This tells us that 1 mole of O2 reacts with 2 moles of Mg to produce 2 moles of MgO.
Calculate the molar mass of O2. Oxygen (O) has an atomic mass of approximately 16 g/mol, so O2 has a molar mass of 32 g/mol.
Determine the number of moles of O2 available. Use the formula: \( \text{moles of O}_2 = \frac{\text{mass of O}_2}{\text{molar mass of O}_2} \). Substitute the given mass of O2 (4.3 g) and the molar mass (32 g/mol) into the formula.
Use the stoichiometry of the reaction to find the moles of MgO produced. According to the balanced equation, 1 mole of O2 produces 2 moles of MgO. Multiply the moles of O2 by 2 to find the moles of MgO.
Calculate the mass of MgO produced using its molar mass. The molar mass of MgO is approximately 40.3 g/mol. Use the formula: \( \text{mass of MgO} = \text{moles of MgO} \times \text{molar mass of MgO} \).