Question

The molar concentration of water in pure water is _______ (rounded off to 1 decimal).

Hint:

1 L of water ≈ 55.5 mol → useful for ionic equilibrium calculations.

Answer 1

Correct Answer: 55.5

Step 1: Density of water = 1 g/mL = 1000 g/L.
Molecular weight = 18 g/mol. Step 2: Calculate molarity.
\[ \text{Moles of water in 1 L} = \frac{1000}{18} = 55.56 \] \[ \Rightarrow \text{Molar concentration} = 55.5~\text{M} \] Step 3: Conclusion.
Molarity of pure water = 55.5 M.