An aqueous solution of NaOH has a mass percentage of 10 % . The ratio of the number of moles of water to the number of moles of NaOH in the solution is ________. (Integer answer) (Given: Molar mass of NaOH = 40 g mol ⁻¹ , Molar mass of H ₂ O = 18 g mol ⁻¹ )

Step-by-step solution

Let the total mass of the aqueous solution be 100 g . Mass of NaOH = 10 g Mass of water = 100 - 10 = 90 g Number of moles of NaOH ( n_ NaOH ) = 10 40 = 0.25 mol Number of moles of water ( n_ H ₂ O ) = 90 18 = 5 mol Ratio of moles of water to moles of NaOH = n_ H ₂ O n_ NaOH = 5 0.25 = 20 Answer: 20