How many moles are present in 11.5 g of sodium?

Options

A. `0.05` mole
B. `5.0` mole
C. 1.5 mole
D. 0.5 mole

Explanation

To find the number of moles present in 11.5 g of sodium, we can follow these steps:

### Step 1: Understand the concept of a mole
A mole is a unit in chemistry that represents a specific number of particles, which is approximately \(6.022 \times 10^{23}\) particles (Avogadro's number). It is used to quantify the amount of a substance.

### Step 2: Identify the molar mass of sodium
The molar mass of sodium (Na) is given as 23 grams per mole (g/mol). This means that 1 mole of sodium weighs 23 grams.

### Step 3: Use the formula to calculate moles
The formula to calculate the number of moles (\(n\)) from mass (\(m\)) and molar mass (\(M\)) is:
\[ n = \frac{m}{M} \]
Where:
- \(n\) = number of moles
- \(m\) = mass of the substance in grams
- \(M\) = molar mass of the substance in grams per mole

### Step 4: Substitute the values into the formula
Given:
- Mass of sodium (\(m\)) = 11.5 g
- Molar mass of sodium (\(M\)) = 23 g/mol

Now substitute these values into the formula:
\[ n = \frac{11.5 \, \text{g}}{23 \, \text{g/mol}} \]

### Step 5: Perform the calculation
\[ n = \frac{11.5}{23} = 0.5 \, \text{moles} \]

### Final Answer
The number of moles present in 11.5 g of sodium is **0.5 moles**.

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