SCH 4U1
SOLUTION EQUILIBRIA
SOME COMPOUNDS ARE SOLUBLE IN WATER AND SOME DO NOT DISSOLVE IN WATER.
SATURATED SOLUTION OF AN "INSOLUBLE" SALT IS A HETEROGENEOUS EQUILIBRIUM.
A
CaCO3(s) <==> Ca2+(aq) + CO32-(aq)
A SMALL CONCENTRATION OF CALCIUM ION AND CARBONATE ANION STILL EXIST IN
SOLUTION EVEN THOUGH THE SALT IS INSOLUBLE.
SINCE THE CONCENTRATION OF CaCO3(s) REMAINS CONSTANT, IT CAN BE ELIMINATED FROM
THE EQUILIBRIUM CONSTANT EXPRESSION. THIS CONSTANT IS CALLED THE SOLUBILITY PRODUCT
CONSTANT, Ksp.
Ksp = [Ca2+][CO32-]
EX. 1 GIVE THE Ksp EXPRESSION FOR THE FOLLOWING EQUILIBRIA.
SOL. 1
a)
a) BaCrO4(s) <-> Ba2+(aq) + CrO42-(aq)
b) Ag3PO4(s) <-> 3 Ag1+(aq) + PO43-(aq)
Ksp =
b)
Ksp =
EX. 2 IF 1.0 L OF WATER IS ABLE TO DISSOLVE 7.1 x 10-7 mol OF AgBr, WHAT IS THE Ksp FOR THIS SALT.
AgBr(s) <==> Ag1+(aq) +
INIT. CONC (M)
Br1-(aq)
0.0
0.0
CHANGE (M)
+7.1 x 10-7
+7.1 x 10-7
EQU'M CONC (M)
_________
________
Ksp = ____________
Ksp = (
)(
)
Ksp = _____________
EX. 3. THE MOLAR SOLUBILITY OF SILVER CHROMATE IN PURE WATER IS 6.7 x 10-5 mol/L, CALCULATE
THE Ksp.
Ag2CrO4(s) <==> 2 Ag1+(aq) +
CrO42-(aq)
INIT. CONC (M)
CHANGE (M)
(
EQU'M CONC (M)
Ksp = _______________
Ksp = _______________
Ksp = _______________
0.0
)
_________
0.0
+_________
________