Transcript Chapter 8 Solutions - South Webster High School

Solutions
Properties of Water
Solutions
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Water
 Most common solvent
 A polar molecule
O a hydrogen bond
H +
H +
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Hydrogen Bonds Attract Polar
Water Molecules
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Hydrophobic – water hating
Hydrophilic – Water loving
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Solute and Solvent
Solutions are homogeneous mixtures of
two or more substances
Solute
The substance in the lesser amount
or what is dissolving
Solvent
The substance in the greater amount
or what is doing the dissolving
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Concentrating – the process
of adding more solute or
taking away solvent
Diluting – the process of
adding more solvent or taking
away solute
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Nature of Solutes in Solutions
Spread evenly throughout the solution
Cannot be separated by filtration
Can be separated by evaporation
Not visible, solution appears
transparent
May give a color to the solution
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Types of Solutions
air
O2 gas and N2 gas
gas/gas
soda
CO2 gas in water
gas/liquid
seawater
NaCl in water
solid/liquid
brass
copper and zinc
solid/solid
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Other solutions
1. Water and sugar – Syrup
2. NaCl and water – Brine
3. (.15 M) NaCl in water – saline
4. CO2 and water – seltzer
5. NH3 gas and water – ammonia
water
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Like dissolves like
A ____________ solvent such as water is
needed to dissolve polar solutes such as
sugar and ionic solutes such as NaCl.
A ___________solvent such as hexane
(C6H14) is needed to dissolve nonpolar
solutes such as oil or grease.
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Rate of Solution
Three things that help dissolve a
solid into a liquid:
Crush it
Use hot water (increase temperature)
Stir it
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Rate of Solution
Three things that help dissolve a gas
into a liquid:
Increase pressure
Decrease temperature
Mix
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Solubility
The maximum amount of solute that
can dissolve in a specific amount of
solvent is usually 100 g.
g of solute
100 g water
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Saturated and Unsaturated
 A saturated solution contains the maximum
amount of solute that can dissolve.
Undissolved solute remains.
 An unsaturated solution does not contain all
the solute that could dissolve
 A supersaturated solution is beyond
the normal amount of solute in
a solvent.
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Temperature and Solubility of
Solids
Temperature Solubility
KCl(s)
0°
27.6
20°C
34.0
50°C
42.6
100°C
57.6
(g/100 g H2O)
NaNO3(s)
74
88
114
182
The solubility of most solids increases
with an increase
in Timberlake
the temperature.15
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Temperature and Solubility of
Gases
Temperature
0°C
20°C
50°C
Solubility (g/100 g H2O)
CO2(g)
O2(g)
0.34
0.17
0.076
0.0070
0.0043
0.0026
The solubility of gases decreases with an
increase in temperature.
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Solubility Rules
1. A salt is soluble in water if it contains
any one of the following ions: (group 1)
NH4+
Li+
Na+
K+
Examples:
soluble salts
LiCl
Na2SO4
KBr
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Nitrates NO32. Salts Containing Nitrate ion (NO3)
Are generally soluble
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Cl- Salts
3. Salts with Cl-, Br-, and I- are soluble, but
not if the positive ion is Ag+, Pb2+, or
Hg22+.
Examples:
soluble
not soluble(will not dissolve)
MgCl2
AgCl
PbCl2
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Silver Salts
4. Most silver salts are insoluble.
AgNO3 and Ag(C2H3O2) are
common soluble salts of silver.
These are the exceptions.
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SO42- Salts
5. Salts with SO42- are soluble, but not if
the positive ion is Ba2+, Pb2+, Ag2+, Hg2+
or Ca2+.
Examples:
soluble
not soluble
MgSO4
BaSO4
PbSO4
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Hydroxide Salts
6. Hydroxide Salts of group I are
soluble. Hydroxide salts of group
II are slightly soluble, and
hydroxide salts of transition
metals and Aluminum are
insoluble.
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Other Salts
7. Most salts containing CO32-, PO43-, S2-,
CrO4-2, F-1 and OH- are not soluble.
Examples:
soluble
not soluble
Na2CO3
CaCO3
K 2S
CuS
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8. All acetates are soluble
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9. All oxides are insoluble
except for CaO and BaO
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Miscible – liquids will mix
together
Immiscible – liquids will not
mix together
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Solutions
Colloids and Suspensions
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Properties of Solutions
1. Have small particles (ions or molecules)
2. Are transparent Do not scatter light.
3. Do not separate
4. Cannot be filtered
5. Are homogeneous
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Properties cont’d
6. Has a saturation point
7. is an electrolyte if ionic
8. osmotic pressure increases as
solute increases
9. Boiling point increases as
solute increases
10. Melting point and vapor
pressur deceases as solute
increases
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# 8, 9 and 10 are colligative
properties (means they are
dependent only on the number
of particle of solute rather than
the type of particle or mass of
material in solution
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Colloidal properties
1. Have medium size particles
2. Cannot be filtered
3. Separated with semipermeable membranes
4. Scatter light (Tyndall effect)
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Properties continued
5. Not homogeneous
6. No saturation point
7. Can be coagulated
8. Only small effect on
colligative properties
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Examples of Colloids
 Emulsion - liquids or solids with liquids
dispersed

Aerolsols – a gas as a dispersing
medium and a solid or liquid dispersant

Foam – liquids or solids with a gas
dispersed into them

Sol – liquid or solid with a solid
dispersed in it.
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Suspensions properties
 Have very large particles
 Settle out
 Can be filtered
 Must stir to stay suspended
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Examples of Suspensions
 Blood platelets
 Muddy water
 Calamine lotion
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