Ksp of Ca(Oh)2
Introduction:
Calcium hydroxide is a soft white caustic powder used in making mortar, cements, calcium salts, paints, and petrochemicals. It is also used in saltwater aquaria to make up kalkwasser/limewater solutions for reef tanks, and is used as a pH regulating agent. Notice that calcium hydroxide is divalent and thus has twice the neutralizing power as molecules like NaOH that are monovalent.
A Calcium Hydroxide Molecule:
Calcium hydroxide is manufactured industrially by adding water to calcium oxide (quicklime) in a strongly exothermic reaction: CaO(s) + H2O(l) → Ca(OH)2(s)
Calcium hydroxide, Ca(OH)2, is an ionic solid that is only slightly soluble in water.
Solid Calcium Hydroxide:
A calcium hydroxide solution is also referred to as limewater. A saturated solution of calcium hydroxide has the solid in equilibrium with its ions as shown below:
Ca(OH)2(s) ↔ Ca2+(aq) + 2OH-(aq)
Recall that a saturated solution is a solution that contains the maximum amount of dissolved solute possible at a given temperature. (The solution contains undissolved solute in equilibrium with the solution.)
Since calcium hydroxide is only slightly soluble in water, it is a difficult base to classify. It is often assumed that since calcium hydroxide has a low solubility that it is a weak base. But, don’t forget that it contains hydroxides ions, which automatically makes it a strong base! In fact, the pH of a saturated calcium hydroxide solution is about 12.4. Thus we can classify a saturated solution of calcium hydroxide as a dilute solution of a strong base.
A molecular view of a saturated solution of calcium hydroxide would look similar to the following, with clumps of undissolved calcium hydroxide at the bottom of the beaker in equilibrium with dissolved Ca2+ and OH- ions (although their would be twice as many OH- ions than Ca2+ ions):
[pic]
Note that the rate of
Calcium hydroxide is a soft white caustic powder used in making mortar, cements, calcium salts, paints, and petrochemicals. It is also used in saltwater aquaria to make up kalkwasser/limewater solutions for reef tanks, and is used as a pH regulating agent. Notice that calcium hydroxide is divalent and thus has twice the neutralizing power as molecules like NaOH that are monovalent.
A Calcium Hydroxide Molecule:
Calcium hydroxide is manufactured industrially by adding water to calcium oxide (quicklime) in a strongly exothermic reaction: CaO(s) + H2O(l) → Ca(OH)2(s)
Calcium hydroxide, Ca(OH)2, is an ionic solid that is only slightly soluble in water.
Solid Calcium Hydroxide:
A calcium hydroxide solution is also referred to as limewater. A saturated solution of calcium hydroxide has the solid in equilibrium with its ions as shown below:
Ca(OH)2(s) ↔ Ca2+(aq) + 2OH-(aq)
Recall that a saturated solution is a solution that contains the maximum amount of dissolved solute possible at a given temperature. (The solution contains undissolved solute in equilibrium with the solution.)
Since calcium hydroxide is only slightly soluble in water, it is a difficult base to classify. It is often assumed that since calcium hydroxide has a low solubility that it is a weak base. But, don’t forget that it contains hydroxides ions, which automatically makes it a strong base! In fact, the pH of a saturated calcium hydroxide solution is about 12.4. Thus we can classify a saturated solution of calcium hydroxide as a dilute solution of a strong base.
A molecular view of a saturated solution of calcium hydroxide would look similar to the following, with clumps of undissolved calcium hydroxide at the bottom of the beaker in equilibrium with dissolved Ca2+ and OH- ions (although their would be twice as many OH- ions than Ca2+ ions):
[pic]
Note that the rate of