You add an excess of Ca(OH)2 to water maintained at a particular temperature, st

Question

You add an excess of Ca(OH)2 to water maintained at a particular temperature, stir until the solution is saturated, filter, then determine the [OH?] in the solution by titration with acid. Titration of 25 mL of the calcium hydroxide solution to the endpoint requires 12.15 mL of 0.070M HCl solution. a) What is the millimolar quantiy of OH? in the 25 mL of solution? b) What are the concentrations of Ca2+ and OH?? c) What is the solubility of Ca(OH)2 under these conditions? (Expressed as g/dL). d) What is the Ksp for Ca(OH)2 under these conditions?

Explanation / Answer

Instead of checking the concentration of OH- ions in the 25ml sample, it is better to determinr the molarity of the Ca(OH)2 solution directly: Equation: Ca(OH)2 + 2HCl ? CaCl2 + 2H2O 1mol Ca(OH)2 reacts with 2mol HCl Use the equation Ma * Va / na = Mb*Vb/nb substitute: 0.055*6.64/2 = Mb * 15/1 Mb = 0.055*6.64*1 / (2*15) Mb = 0.0122M Ca(OH)2 Molarity of the Ca(OH)2 solution = 0.0122M Concentration of Ca2+ ions = 0.0122M Concentartion of OH- ions = 0.0244M Ksp = [Ca 2+] * [OH-]² Ksp = 0.0122 * 0.0244² Ksp = 7.26*10^-6 aprox

Related Questions

Navigate

• Browse (All)
• Browse Y
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.