A concentrated aqueous hydrofluoric acid solution has a density of 1.15 g/mL and is 48.0% by mass HF (20.01 g/mol).Determine the molar concentration of this solution.

Question

Quizplus · Accepted Answer

The molar concentration (M) of the solution can be calculated by dividing the moles of solute (HF in this case) by the volume of the solution in liters. First, we find the mass of HF in 1000 mL (or 1 L) of solution, given that the solution is 48.0% HF by mass and has a density of 1.15 g/mL. The mass of the solution per liter is 1150 g (since 1 mL = 1 g and we have 1000 mL), and 48.0% of this mass is HF: $1150 g \times 0.48 = 552 g$ of HF. To find the moles of HF, we divide the mass of HF by its molar mass: $552 g \div 20.01 g/mol = 27.6$ moles. Therefore, the molar concentration is 27.6 M.

A Concentrated Aqueous Hydrofluoric Acid Solution Has a Density of 1.15