Question

A 6.50 molal solution of KOH (aq.) has a density of 1.89 g cm⁻³. The molarity of the solution is ______ mol dm⁻³. (Round off to the Nearest Integer)

[Atomic masses: K: 39.0 u; O: 16.0 u; H: 1.0 u]

Options

• 3

• 5

• 7

• 9

Answer 1

A 6.50 molal solution of KOH (aq.) has a density of 1.89 g cm⁻³. The molarity of the solution is 9 mol dm⁻³.

Explanation:

m = `(1000 xx "M")/((1000 xx "d" - "M" xx "M"_"solute"))`

6.5 = `(1000 xx "M")/(1890 - "M" xx 56)`

12285 – 364 M = 1000 M

1364 M = 12285

M = 9