Question

Which of the following methods of expressing concentration are unitless?

• A. Molality and Mole fraction
• B. Mass percent (W/W) and Molality
• C. Molality and Molality
• D. Mole fraction and Mass percent (W/W)

Hint:

Mass percent and mole fraction are unitless, making them useful for comparing concentrations across different substances.

Answer 1

The Correct Option is D

Mole fraction and mass percent (W/W) are unitless because both are mass ratios. The mole fraction is the ratio of the number of moles of one component to the total number of moles in the solution, and mass percent is the ratio of the mass of one component to the total mass of the solution. Neither of these ratios requires any units.