Molarity of pure water is
A. `18 M`
B. `10 M`
C. `55.5 M`
D. `1000 M`
A. `18 M`
B. `10 M`
C. `55.5 M`
D. `1000 M`
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Correct Answer – C
Molarity of pure water implies the number of moles of `H_(2) O` per liter of water. Since the density of `H_(2) O` is `1g mL^(-1)`, the mass of `1L (1000 mL)` of water will be `1000g`. Thus, the number of moles of `H_(2) O` in `1000g` will be
`n_(H_(2)O) = (“Mass of” H_(2) O)/(“Molar Mass of” H_(2) O) = (1000g)/(18.0g mol^(-1)) = 55.5 mol`
As these moles are present in `1L` of `H_(2) O`, we say that molarity `(mol L^(-1))` of `H_(2)O` is `55.5M`.