Chemistry Forum

An aqueous solution is 0.10 M in both sulfate ion and chromate ion. Powdered lead nitrate(Ⅱ) is slowly dissolved in the well-stirred solution. (Assume no volume change).

(a) What is the concentration of Pb²⁺ when PbSO₄ first start to precipitate?

(b)What is the concentration of Pb²⁺ when PbCrO₄ first start to precipitate?

(c) Which compound precipitate first?

(d)When the second anion just start to precipitate, what is the molar concentration of the anion that precipitate first?

I am working on all these questions. If any member knows correct answers, may reply those answers.

Hint: solubility product.

These questions are currently occupying my time. Any member who knows the proper answers can reply with them.

As I wrote check the solubility products of both.
With them you can calculate the lead concentration.

Answers

(a)[Pb²⁺] = 1.6 ⨯ 10⁻⁸ ÷ 0.10 =1.6⁻⁷

(b)[Pb²⁺] = 1.7 ⨯ 10⁻¹⁴ ÷ 0.10 = 1.7 ⨯ 10⁻¹³

(c)PbCrO₄ will precipitate first.

(d) CrO₄²⁻ = 1.7 ⨯ 10⁻¹⁴ ÷ 1.6 ⨯ 10⁻⁸ = 1.1 ⨯ 10⁻⁶