Calculate the number of moles :
7.85 g of Fe

Answer

To calculate the number of moles in 7.85 g of Fe (iron), follow these steps:

### Step 1: Determine the atomic mass of iron (Fe)
The atomic mass of iron (Fe) is approximately 55.85 g/mol. This means that one mole of iron weighs 55.85 grams.

### Step 2: Use the formula to calculate moles
The formula to calculate the number of moles (n) is given by:

\[ n = \frac{\text{mass (g)}}{\text{molar mass (g/mol)}} \]

### Step 3: Plug in the values
In this case, the mass of iron is 7.85 g, and the molar mass of iron is 55.85 g/mol. Substituting these values into the formula gives:

\[ n = \frac{7.85 \text{ g}}{55.85 \text{ g/mol}} \]

### Step 4: Perform the calculation
Now, calculate the value:

\[ n = \frac{7.85}{55.85} \approx 0.140 \]

### Step 5: State the final answer
Thus, the number of moles of iron in 7.85 g of Fe is approximately 0.14 moles.

### Summary of the Solution
The number of moles of 7.85 g of Fe is 0.14 moles.

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