Molarity of pure water is

Options

A. `1M`
B. 55.55m
C. 27.73m
D. 80.55m

Answer

To find the molarity of pure water, we need to follow these steps:

### Step 1: Understand Molarity
Molarity (M) is defined as the number of moles of solute per liter of solution. In this case, we are considering pure water as the solvent.

### Step 2: Calculate the Mass of Water
Since we are looking for the molarity of pure water, we start by noting that 1 liter of water has a mass of approximately 1000 grams (since the density of pure water is 1 g/mL).

### Step 3: Determine the Molar Mass of Water
The molar mass of water (H₂O) can be calculated as follows:
- Hydrogen (H) has a molar mass of approximately 1 g/mol.
- Oxygen (O) has a molar mass of approximately 16 g/mol.
- Therefore, the molar mass of water (H₂O) = (2 × 1) + (1 × 16) = 2 + 16 = 18 g/mol.

### Step 4: Calculate the Number of Moles of Water
To find the number of moles of water in 1 liter (1000 grams), we use the formula:
\[ \text{Number of moles} = \frac{\text{mass}}{\text{molar mass}} \]
Substituting the values:
\[ \text{Number of moles} = \frac{1000 \text{ g}}{18 \text{ g/mol}} \approx 55.56 \text{ moles} \]

### Step 5: Calculate Molarity
Since we have approximately 55.56 moles of water in 1 liter, the molarity of pure water is:
\[ \text{Molarity} = \frac{\text{Number of moles}}{\text{Volume in liters}} = \frac{55.56 \text{ moles}}{1 \text{ L}} = 55.56 \text{ M} \]

### Conclusion
The molarity of pure water is approximately 55.56 M.

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