Question

What is the pH of a solution made by dissolving 7.91 grams of calcium fluoride in enough water to make 6.0×102 mL of solution? The Ka for HF is 6.8x10–4.

Answer 1

Ans. #Step 1: [CaF₂] = Moles / Vol. in liters = (Mass / MW) / Vol. in liters

                                    = (7.91 g / 78.0748064 g/ mol) / 0.600 L

                                    = 0.169 M

# 1 mol CaF₂ consists of 2 mol F^-.

So,

            [F^-] = 2 x [CaF₂] = 2 x 0.169 M = 0.338 M

# Step 2: