The mass of magnesium oxide formed by burning 1.216 g magnesium in excess oxygen is

Options

A. 0.416 g
B. 1.616 g
C. 2.016 g
D. 2.816 g

Explanation

To find the mass of magnesium oxide (MgO) formed by burning 1.216 g of magnesium (Mg) in excess oxygen, we can follow these steps:

### Step 1: Write the balanced chemical equation
The reaction between magnesium and oxygen can be represented by the balanced equation:
\[ 2 \text{Mg} + \text{O}_2 \rightarrow 2 \text{MgO} \]
This equation tells us that 2 moles of magnesium react with 1 mole of oxygen to produce 2 moles of magnesium oxide.

### Step 2: Calculate the molar mass of magnesium and magnesium oxide
- The molar mass of magnesium (Mg) is approximately 24 g/mol.
- The molar mass of magnesium oxide (MgO) is calculated as follows:
- Molar mass of Mg = 24 g/mol
- Molar mass of O = 16 g/mol
- Therefore, molar mass of MgO = 24 + 16 = 40 g/mol

### Step 3: Determine the amount of magnesium in moles
To find the number of moles of magnesium in 1.216 g, we use the formula:
\[ \text{Moles of Mg} = \frac{\text{mass of Mg}}{\text{molar mass of Mg}} = \frac{1.216 \text{ g}}{24 \text{ g/mol}} \approx 0.05067 \text{ moles} \]

### Step 4: Use the stoichiometry of the reaction
From the balanced equation, we see that 2 moles of magnesium produce 2 moles of magnesium oxide. Therefore, the moles of magnesium oxide produced will be equal to the moles of magnesium reacted:
\[ \text{Moles of MgO} = \text{Moles of Mg} = 0.05067 \text{ moles} \]

### Step 5: Calculate the mass of magnesium oxide produced
Now, we can calculate the mass of magnesium oxide produced using its molar mass:
\[ \text{Mass of MgO} = \text{Moles of MgO} \times \text{Molar mass of MgO} = 0.05067 \text{ moles} \times 40 \text{ g/mol} \approx 2.027 \text{ g} \]

### Conclusion
The mass of magnesium oxide formed by burning 1.216 g of magnesium in excess oxygen is approximately **2.027 g**.

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