Download 7.6Predicting Precipitation

Predicting Precipitation
SCH 4U1
Environmental scientists are often concerned with water quality
and are interested to know the threshold for ion precipitation.
If the ion product, Q > Ksp the precipitate will form.
If the ion product, Q = Ksp the precipitate will just begin to form
(saturated).
If the ion product, Q < Ksp the precipitate will not form
(unsaturated).
Ex 1.
A chemical analyst mixes two solutions containing 500.0 mL of
0.020 M NaCl solution and 500.0 mL of a 0.15 M Pb(NO3)2
solution.
a) what is the potential precipitate, equilibrium expression?
b) what is the Ksp value (p. 802 - Appendix C) and K expression?
c) what is the ion product, Q?
d) will a precipitate form?
Answer
a) _________________________
b) Ksp = ___________, Ksp = ___________
c) Q = ___________________
Q = ___________________
Q = ___________________
d) Since the Q< Ksp there will be __ precipitate.