The weight in grams of KCl (Mol.wt. = 74.5) in 100 ml of a 0.1 M KCl solution is

Options

A. `74.5`
B. 2024
C. `0.745`
D. `0.0745`

Explanation

To find the weight of KCl in a 100 ml of a 0.1 M KCl solution, we can follow these steps:

### Step 1: Understand the formula for molarity
Molarity (M) is defined as the number of moles of solute per liter of solution. The formula is:
\[ M = \frac{\text{Number of moles of solute}}{\text{Volume of solution in liters}} \]

### Step 2: Convert the volume from milliliters to liters
We are given the volume of the solution as 100 ml. To convert this to liters:
\[ \text{Volume in liters} = \frac{100 \text{ ml}}{1000} = 0.1 \text{ L} \]

### Step 3: Calculate the number of moles of KCl
We know the molarity (0.1 M) and the volume (0.1 L). We can rearrange the molarity formula to find the number of moles:
\[ \text{Number of moles} = M \times \text{Volume in liters} \]
\[ \text{Number of moles} = 0.1 \times 0.1 = 0.01 \text{ moles} \]

### Step 4: Use the molecular weight to find the weight of KCl
The molecular weight of KCl is given as 74.5 g/mol. To find the weight of KCl in grams, we use the formula:
\[ \text{Weight} = \text{Number of moles} \times \text{Molecular weight} \]
\[ \text{Weight} = 0.01 \text{ moles} \times 74.5 \text{ g/mol} = 0.745 \text{ g} \]

### Conclusion
The weight of KCl in 100 ml of a 0.1 M KCl solution is **0.745 grams**.

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