Question

Molarity of pure water is:

Hint:

For molarity of pure liquids, use density and molar mass: $M = \dfrac{\text{density} \times 1000}{\text{molar mass}}$.

Answer 1

Step 1: Definition of molarity.
Molarity (M) = $\dfrac{\text{Number of moles of solute}}{\text{Volume of solution in litres}}$.

Step 2: Find moles of water.
- Molar mass of water = 18 g mol$^{-1}$.
- Density of water = 1000 g L$^{-1}$.
So, number of moles in 1 L of water = $\dfrac{1000}{18} = 55.56$ mol.

Step 3: Conclusion.
Thus, the molarity of pure water is 55.56 mol L$^{-1}$.

Final Answer: \[ \boxed{55.56 \ \text{mol L}^{-1}} \]