Answer to Question #140947 in Chemistry for Hanna Faith Dagar

Question

What is the molarity of concentrated HF in the solution is 48% HF by mass and has a density of 1.17g/mL?

Answer 1

Solution:

1) Determine the moles of HF in 100.0 grams of 48.0% solution:

48.0 g of the 100.0 g is HF

Moles of HF = Mass of HF / Molar mass of HF

The molar mass of HF is 20.01 g/mol.

Hence,

Moles of HF = 48.0 g / 20.01 g mol^-1 = 2.3988 mol

2) Calculate the volume of solution which contains 2.3988 mol of HF:

Volume of solution = Mass of solution / Density of solution

Hence,

V_solution = 100.0 g / 1.17 g mL^-1 = 85.47 mL = 0.08547 L

3) Calculate the molarity of solution:

C_M = Moles of HF / Volume of solution

Hence,

C_M = 2.3988 mol / 0.08547 L = 28.066 mol/L = 28.1 M

Answer: the molarity (C_M) of concentrated solution of HF is 28.1 M.