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SolutionsSolutions
SOLUTE + SOLVENT SOLUTION
State of MatterState of Matter
homogenous mixture of gases (Air…)
Gas:Gas:
solvent: liquid solute: liquid(ethanol in water)
solvent: liquid solute: gassolid
(soda water: CO2/H2O; brine: NaCl/H2O)
Liquid:Liquid:
solvent: solid solute: liquid(Dental-filling alloy)
solvent: solid solute: solid(gold-silver alloy)
Solid:Solid:
Dissolve: solute + solvent solution.
Crystallization: solution solute + solvent.
Saturation: crystallization and dissolution are in equilibrium.
Solubility: amount of solute required to form a saturated solution.
Supersaturated: a solution formed when more solute is dissolved than in a saturated solution.
Miscible: two liquids that mix.
Immiscible: two liquids that do not mix.
Terms to Know…
Like Dissolves Like
“Rule”: polar solvents dissolve
polar solutes. Non-polar solvents
dissolve non-polar solutes. Why?
If ΔHsoln is too endothermic a
solution will not form.
NaCl in octane (C8H18): the ion-
London forces are weak because
octane is non-polar. Therefore,
the ion-London forces do not
compensate for the separation of
ions.
NaCl dissolves nicely in water.
+ –+–
+ –
+ –+–
+ –
NaCl
octane
water
Terminology:
Solubility: is the maximum amount of the solute that will dissolve in a definite amount of solvent (at a given t°)
g/100 mL
Concentration: ratio of the solute and the solvent
Dilute solutionsConcentrated solutions
Saturated solutions:
solutepure solute dissolved
Supersaturated solutions:
g/100 mL KNO3
PbCl2
NaCl
Solubility curves t°
Temperature Effects: Solids
• Experience tells us that sugar dissolves better in warm water than cold.
• As temperature increases, solubility of solids generally increases.
• Sometimes, solubility decreases as temperature increases (e.g. Ce2(SO4)3).
Properties of Water
Most abundant liquid
Vital to life
Universal solvent
1. High melting and boiling points
M.p.: 0.0°CB.p.: 100.0°C (0.1 MPa)
Hydrogen Bonding
Special case of dipole-dipole forces.By experiments: boiling points of compounds with H-F, H-O, and H-N bonds are abnormally high.Intermolecular forces are abnormally strong.
-200
-150
-100
-50
0
50
100
150
0 1 2 3 4 5
Period
Bo
ilin
g P
oin
t (d
eg C
)
Group 4
Group 5
Group 6
Group 7
CH4
SnH4
GaH4SiH4
H2O
H2SH2Se
H2Te
Water Molecule
Solutions
Phase Diagram of H2O
The melting point curve slopes to the left because ice is less dense than water.Triple point occurs at 0.0098°C and 4.58 mmHg.Normal melting (freezing) point is 0°C.Normal boiling point is 100°C.Critical point is 374°C and 218 atm.
2. Density
0.0°C (ice) 0.91680 g/cm3
0.0°C (liquid) 0.99984 g/cm3
3.98°C 0.99997 g/cm3
25.0°C 0.99704 g/cm3
3. Surface tension: high
Bottom of meniscus
4. High heat of vaporization
40.70 kJ/mol
5. High heat of fusion
6.02 kJ/mol
6. High specific heat
75.20 kJ/mol
1. Chemically pure water
2. Water of crystallization or hydration
CuSO4 5H2O(s) CuSO4(s) + 5H2O(g)
(CaSO4)2 H2O (plaster of paris)
CaSO4 2H2O (gypsum)
Na2CO3 10H2O
3. Groundwater
CationsCations AnionsAnions
Ca2+ HCO3-, CO3
2-
Na+ OH-
Mg2+ SO42-
K+ Cl-
Fe2+, Fe3+ NO3-
NH4+ F-, PO4
3-
Hard water Soft water
Water Softening
Temporary hard water HCO3
- (bicarbonate) Permanent hard water
Boiling Softening agents precipitation
complex formation Distillation Ion-exchange
Mineral waterThermal water