Calculate the mass of Mg (atomic mass = 24 g'mol) that combines with 1.5 mol of `O_2` to form magnesium oxide (MgO)

Options

A. 24 g
B. 36 g
C. 48 g
D. 72 g

Answer

To solve the problem of calculating the mass of magnesium (Mg) that combines with 1.5 moles of oxygen (O₂) to form magnesium oxide (MgO), we can follow these steps:

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

### Step 2: Determine the moles of magnesium required
From the balanced equation, we see that 1 mole of O₂ requires 2 moles of Mg. Therefore, if we have 1.5 moles of O₂, we can calculate the moles of Mg needed:
\[ \text{Moles of Mg} = 1.5 \text{ moles O}_2 \times \frac{2 \text{ moles Mg}}{1 \text{ mole O}_2} = 3 \text{ moles Mg} \]

### Step 3: Calculate the mass of magnesium
Now that we know we need 3 moles of magnesium, we can calculate the mass using the atomic mass of magnesium, which is 24 g/mol:
\[ \text{Mass of Mg} = \text{Moles of Mg} \times \text{Atomic mass of Mg} \]
\[ \text{Mass of Mg} = 3 \text{ moles} \times 24 \text{ g/mol} = 72 \text{ grams} \]

### Conclusion
The mass of magnesium that combines with 1.5 moles of O₂ to form magnesium oxide is **72 grams**.

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