solutions
DESCRIPTION
Solutions. Solution Saturation. Compares the amount of dissolved solute in a solution with the maximum amount of dissolved solute possible under the given conditions. UNSATURATED SOLUTION more solute dissolves. SATURATED SOLUTION no more solute dissolves. SUPERSATURATED SOLUTION - PowerPoint PPT PresentationTRANSCRIPT
Solution Saturation
Compares the amount of dissolved solute in a solution with the maximum amount of dissolved solute possible under the given conditions.
SolubilitySATURATED SOLUTION
no more solute dissolves
UNSATURATED SOLUTIONmore solute
dissolves
SUPERSATURATED SOLUTION
becomes unstable, crystals form
increasing concentration
Solubility
• A solution that contains the maximum possible amount of solute is saturated.
• If a solution contains less than the maximum amount of solute, it is unsaturated.
Solubility• When a solution is saturated and excess
solute is present, the rate of dissolution is equal to the rate of crystallization.
• Solubility increases with increasing temperature — a saturated solution that was prepared at a higher temperature contains more dissolved solute than it would contain at a lower temperature, when the solution is cooled, it can become supersaturated.
Solubility vs. Temperature
Timberlake, Chemistry 7th Edition, page 297
KI
NaNO 3
KN
O 3
Na 3PO 4
NaCl
Temperature (oC)
Sol
ubili
ty (
g so
lute
/ 10
0 g
H2O
)200
180
160
140
120
100
80
60
40
20
020 40 60 80 100
Gas SolubilityCH4
O2
CO
He
Temperature (oC)
Sol
ubili
ty (
mM
)
2.0
1.0
0 10 20 30 40 50
Higher Temperature
…Gas is LESS Soluble
Solubility Table
LeMay Jr, Beall, Robblee, Brower, Chemistry Connections to Our Changing World , 1996, page 517
0 10 20 30 40 50 60 70 80 90 100
Solubility vs. Temperature for Solids
Sol
ubili
ty (
gram
s of
sol
ute/
100
g H
2O)
KI
KCl
20
10
30
40
50
60
70
80
90
110
120
130
140
100
NaNO3
KNO3
HCl NH4Cl
NH3
NaCl KClO3
SO2
shows the dependence
of solubility on temperature
gases
solids
Solubility
SolubilitySolubility
maximum grams of solute that will dissolve
in 100 g of solvent at a given temperature
– Solubility is expressed as (g/L) or (g/g) or (mol/L).
varies with temperature
based on a saturated solution
SolubilitySolubility
Solids are more soluble at...Solids are more soluble at...• high temperatures.
Gases are more soluble at...Gases are more soluble at...• low temperatures &• high pressures
(Henry’s Law).• EX: nitrogen narcosis,
the “bends,” soda
Temp. (oC)
Solubility(g/100 g H2O)
KNO3 (s)
KCl (s)
HCl (g)
SOLUBILITYCURVE
Solubility how much solute dissolves in a given amt.
of solvent at a given temp.
Unsaturated: solution could hold more solute; belowbelow linesaturated: solution has “just right” amt. of solute; onon linesupersaturated: solution has “too much” solute dissolved in it; above the line
To
Sol.
To
Sol.
Solids dissolved in liquids Gases dissolved in liquids
As To , solubility As To , solubility
per100 gH2O
Classify as unsaturated, saturated, or supersaturated.
80 g NaNO3 @ 30oC
45 g KCl @ 60oC
50 g NH3 @ 10oC
70 g NH4Cl @ 70oC
So sat. pt. @ 40oC for 500 g H2O = 5 x 66 g = 330 g
120 g < 330 g unsaturated
saturation point @ 40oC for 100 g H2O = 66 g KNO3
Per 500 g H2O, 120 g KNO3 @ 40oC
unsaturated
saturated
unsaturated
supersaturated
Solubility of Sodium Acetate
Temperature (oC)
025 50 75 100
Sol
ubili
ty(g
/100
g H
2O)
50
100
150Supersaturated
solution
Unsaturated solution
Saturated
Video Clip
Charles H.Corwin, Introductory Chemistry 2005, page 378
A single crystal of sodium acetate, NaC2H3O2, is dropped into a
supersatureated solution
The small crystal causes extensivecrystallization, and eventually
the solute forms a solid mass of NaC2H3O2.