Chapter 8
Solutions
Properties of Water
Solutions
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Predict the % water in the following
foods
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Predict the % water in the following
foods
88% water
94% water
85% water
86% water
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Water in the Body
water gain
liquids
1000 mL
food
1200 mL
cells
300 mL
water loss
urine
1500 mL
perspiring 300 mL
exhaling
600 mL
feces
100 mL
Calculate the total water gain and water loss
Total ______ mL
_____ mL
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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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Explore:
Surface Tension
 Fill a glass to the brim with water
 How many pennies can you add to the
glass without causing any water to run
over?
Predict _________________
Actual _________________
 Explain your results
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Explore
1. Place some water on a waxy surface. Why
do drops form?
2. Carefully place a needle on the surface of
water. Why does it float? What happens if
you push it through the water surface?
3. Sprinkle pepper on water. What does it
do? Add a drop of soap. What happens?
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Surface Tension
 Water molecules within water hydrogen
bond in all directions
 Water molecules at surface cannot hydrogen
bond above the surface, pulled inward
 Water surface behaves like a thin, elastic
membrane or “skin”
 Surfactants (detergents) undo hydrogen
bonding
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Solute and Solvent
Solutions are homogeneous mixtures of
two or more substances
Solute
The substance in the lesser amount
Solvent
The substance in the greater amount
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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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Discussion
Give examples of some solutions
and explain why they are solutions.
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Learning Check SF1
(1) element
(2) compound
(3) solution
A. water
1
2
3
B. sugar
1
2
3
C. salt water
1
2
3
D. air
1
2
3
E. tea
1
2
3
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Solution SF1
(1) element
(2) compound
A. water
2
B. sugar
2
C. salt water
3
D. air
3
E. tea
3
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(3) solution
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Learning Check SF2
Identify the solute and the solvent.
A. brass: 20 g zinc + 50 g copper
solute
=
1) zinc
2) copper
solvent
=
1) zinc
2) copper
B. 100 g H2O + 5 g KCl
solute
=
1) KCl
2) H2O
solvent
=
1) KCl
2) H2O
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Solution SF2
A. brass: 20 g zinc + 50 g copper
solute
solvent
=
=
1) zinc
2) copper
B. 100 g H2O + 5 g KCl
solute
=
1) KCl
solvent
=
2) H2O
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Learning Check SF3
Identify the solute in each of the following
solutions:
A. 2 g sugar (1) + 100 mL water (2)
B. 60.0 mL ethyl alcohol(1) and 30.0 mL
of methyl alcohol (2)
C. 55.0 mL water (1) and 1.50 g NaCl (2)
D. Air: 200 mL O2 (1) + 800 mL N2 (2)
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Solution SF3
Identify the solute in each of the following
solutions:
A. 2 g sugar (1)
B. 30.0 mL of methyl alcohol (2)
C. 50 g NaCl (2)
D. 800 mL N2 (2)
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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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Learning Check SF4
Which of the following solutes will
dissolve in water? Why?
1) Na2SO4
2) gasoline
3) I2
4) HCl
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Solution SF4
Which of the following solutes will
dissolve in water? Why?
1) Na2SO4
Yes, polar (ionic)
2) gasoline
No, nonnpolar
3) I2
No, nonpolar
4) HCl
Yes, Polar
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Formation of a Solution
H2O
Cl- Na+
Na+
H2O Cl-
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solute
Hydration
Dissolved
solute
23
Writing An Equation for a
Solution
When NaCl(s) dissolves in water, the
reaction can be written as
H 2O
NaCl(s)
solid
Na+ (aq) + Cl- (aq)
separation of ions in water
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Learning Check SF5
Solid LiCl is added to some water. It
dissolves because
A. The Li+ ions are attracted to the
1) oxygen atom(-) of water
2) hydrogen atom(+) of water
B. The Cl- ions are attracted to the
1) oxygen atom(-) of water
2) hydrogen atom(+) of water
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Solution SF5
Solid LiCl is added to some water. It
dissolves because
A. The Li+ ions are attracted to the
1) oxygen atom(-) of water
B. The Cl- ions are attracted to the
2) hydrogen atom(+) of water
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Rate of Solution
You are making a chicken broth using a
bouillon cube. What are some things you
can do to make it dissolve faster?

Crush it

Use hot water (increase temperature)

Stir it
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Learning Check SF6
You need to dissolve some gelatin in
water. Indicate the effect of each of the
following on the rate at which the gelatin
dissolves as (1) increase, (2) decrease,
(3) no change
A. ___Heating the water
B. ___Using large pieces of gelatin
C. ___Stirring the solution
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Learning Check SF6
You need to dissolve some gelatin in
water. Indicate the effect of each of the
following on the rate at which the gelatin
dissolves as (1) increase, (2) decrease,
(3) no change
A. 1 Heating the water
B. 2 Using large pieces of gelatin
C. 2 Stirring the solution
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