Which of the statements below are TRUE for expressing the concentration of a 54.9-ppm Fe solution in terms of molarity?
I Iron's molar mass must be known to calculate the moles iron in solution.
II Iron's density must be known to calculate the mass iron in solution.
III The solution density must be known to calculate the solution volume.
IV The type of glassware used to prepare the solution must be known.

Question

Quizplus · Accepted Answer

To express the concentration of a solution in terms of molarity, we need to know the number of moles of solute per liter of solution. Therefore, statement I is true as we need to know the molar mass of iron to calculate the number of moles in 1 liter of solution. Statement II is not required to express concentration in terms of molarity, so it is false. Statement III is true since we need to know the solution density to calculate the volume of solution containing one mole of iron. Statement IV is not necessary to calculate molarity, so it is false. Therefore, the only true statements are I and III, making choice C the best answer.

Which of the Statements Below Are TRUE for Expressing the Concentration