18. Aqueous Equilibrium

Solution contains [Cu²⁺] = 0.035 M, [Sr²⁺] = 0.054 M, [Al³⁺] = 0.23 M. Cu²⁺ can be separated by selective precipitation using NaOH. What is the minimum concentration of NaOH needed to start precipitation of Cu²⁺? (K_sp = 2.2 × 10⁻²⁰ of Cu(OH)₂).

Suppose that a 10-mL sample of a solution is to be tested for I- ion by addition of 1 drop (0.2 mL) of 0.10 M Pb1NO322. What is the minimum number of grams of I- that must be present for PbI21s2 to form?

The water supply for a midwestern city contains the following impurities: coarse sand, finely divided particulates, nitrate ions, trihalomethanes, dissolved phosphorus in the form of phosphates, potentially harmful bacterial strains, dissolved organic substances. Which of the following processes or agents, if any, is effective in removing each of these impurities: coarse sand filtration, activated carbon filtration, aeration, ozonization, precipitation with aluminum hydroxide?

(b) What is the most significant difference between the sulfides precipitated in group 2 and those precipitated in group 3?

Determine the minimum concentration of the precipitating agent on the right to cause precipitation of the cation from the solution on the left. c. 0.0018 M AgNO₃; RbCl