Calculate the concentration of Ca+2 in a saturated solution of Ca(OH)2 if the Ksp = 6.5x10-6 at 25oC.
can someone explain the steps to do this please? :)
.......Ca(OH)2 ==> Ca^2+ + 2OH^-
I......solid........0.......0
C......solid........x.......2x
E......solid........x.......2x
Ksp = (Ca^2)(OH^-)^2
Substitute the E line into the Ksp expression and solve for (Ca^2+). 2x that will be (OH^-) if you want to know that. The solubility of Ca(OH)2 in the saturated solution will be the same as (Ca^2+) if want to know that.
Solubility in pure water of all 1:2 or 2:1 ionizations with Ksp values is => Cube-Rt(Ksp/4).
For Ca(OH)2 ; Ksp=6.5E-5
Solubility = Cube-Rt(6.5E-5/4) = 0.0118M in Ca^+2 and 2(0.0118M)in OH^-.
In pure water (no common ion effect) the following can be used to calculate amount of salt delivering ions into solution ...
for 1:3 Izns => S = 4th-Rt(Ksp/27)
for 1:4 Izns => S = 5th-Rt(Ksp/256)
for 2:3 Izns => S = 5th-Rt(Ksp/108)
To calculate the concentration of Ca+2 in a saturated solution of Ca(OH)2, you need to use the solubility product constant (Ksp) and the stoichiometry of the reaction. Here are the steps to solve this problem:
Step 1: Write the balanced equation for the dissociation of Ca(OH)2.
Ca(OH)2(s) ⟶ Ca+2(aq) + 2OH-(aq)
Step 2: Write the expression for the solubility product constant (Ksp) in terms of the concentrations of the ions.
Ksp = [Ca+2] * [OH-]^2
Step 3: Determine the value of Ksp from the given information.
Given: Ksp = 6.5x10^-6
Step 4: Use stoichiometry to relate the concentration of Ca+2 and OH- ions.
From the balanced equation, 1 mole of Ca(OH)2 produces 1 mole of Ca+2 and 2 moles of OH-.
This means that in equilibrium, [Ca+2] = [OH-]/2.
Step 5: Substitute the relation ([Ca+2] = [OH-]/2) into the Ksp expression.
Ksp = [OH-]^3 / 8
Step 6: Rearrange the equation to solve for [OH-].
[OH-]^3 = 8 * Ksp
[OH-] = (8 * Ksp)^(1/3)
Step 7: Substitute the value of Ksp into the equation and calculate [OH-].
[OH-] = (8 * 6.5x10^-6)^(1/3) ≈ 3.8x10^-2 M
Step 8: Calculate the concentration of Ca+2 using the relation [Ca+2] = [OH-]/2.
[Ca+2] ≈ (3.8x10^-2)/2 ≈ 1.9x10^-2 M
Therefore, the concentration of Ca+2 in a saturated solution of Ca(OH)2 at 25°C is approximately 1.9x10^-2 M.