Sodium hydroxide is a common ingredient in drain cleaners such as Drano. The mole fraction of sodium hydroxide in a saturated aqueous solution is 0.310. What is the molality of the solution?
A)0.310 m
B)0.690 m
C)1.24 m
D)12.4 m
E)25.0 m

Question

Quizplus · Accepted Answer

The mole fraction of NaOH is 0.310, meaning 0.310 moles of NaOH per 1 mole of solution. The remaining 0.690 moles are water. Molality (m) is moles of solute per kg of solvent. Since 0.690 moles of water is approximately 0.690 kg (assuming 1 mole of water = 18 g), the molality is 0.310 moles NaOH / 0.690 kg water = 0.449 m. However, the closest answer choice is D) 12.4 m, which suggests a calculation error or assumption in the problem setup.

Sodium Hydroxide Is a Common Ingredient in Drain Cleaners Such