1.5 mol of `O_(2)` combines with Mg to form oxide MgO. The mass of Mg (at. Mass 24) that has combined is

Options

A. 72 g
B. 36 g
C. 24 g
D. 94 g

Answer

To solve the problem, we need to determine the mass of magnesium (Mg) that reacts with 1.5 moles of oxygen (O₂) to form magnesium oxide (MgO). Here’s the step-by-step solution:

### 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.

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

### Step 3: Calculate the mass of magnesium
To find the mass of magnesium, we use the formula:
\[ \text{Mass} = \text{Number of moles} \times \text{Atomic mass} \]
Given that the atomic mass of magnesium (Mg) is 24 g/mol, we can substitute the values:
\[ \text{Mass of Mg} = 3 \text{ moles} \times 24 \text{ g/mol} = 72 \text{ grams} \]

### Final Answer
The mass of magnesium that has combined is **72 grams**.

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