5.85 g NaCl is dissolved in 500 ml of water. The molarity is

Options

A. `0.1`
B. `0.2`
C. `0.3`
D. `0.4`

Explanation

To calculate the molarity of a solution, we can follow these steps:

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

### Step 2: Convert the volume of the solution from milliliters to liters
The volume of the solution is given as 500 mL. To convert this to liters, we divide by 1000:
\[ \text{Volume in liters} = \frac{500 \text{ mL}}{1000} = 0.5 \text{ L} \]

### Step 3: Calculate the number of moles of solute
To find the number of moles of solute (NaCl), we use the formula:
\[ \text{Number of moles} = \frac{\text{Weight of solute (g)}}{\text{Molecular weight of solute (g/mol)}} \]

The weight of NaCl is given as 5.85 g. Now, we need to find the molecular weight of NaCl:
- The atomic weight of Sodium (Na) = 23 g/mol
- The atomic weight of Chlorine (Cl) = 35.5 g/mol
- Therefore, the molecular weight of NaCl = 23 + 35.5 = 58.5 g/mol

Now, we can calculate the number of moles:
\[ \text{Number of moles} = \frac{5.85 \text{ g}}{58.5 \text{ g/mol}} = 0.1 \text{ moles} \]

### Step 4: Calculate the molarity
Now that we have the number of moles and the volume of the solution, we can calculate the molarity:
\[ \text{Molarity} = \frac{0.1 \text{ moles}}{0.5 \text{ L}} = 0.2 \text{ M} \]

### Conclusion
The molarity of the NaCl solution is 0.2 M.

---