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					Solutions
  Chapter 22
Sections 1 - 4
Solutions

Section 1 How Solutions Form slides 3-14
Section 2 Solubility & Concentration slides
 15-28
Section 3 Particles in Solution slides 29-38
Section 4 Dissolving Without Water slides
 39-49
1 How Solutions Form

What You’ll Learn:
Three types of solutions
How things dissolve
The rate solids and gases dissolve
What is a solution?

A solution is a mixture that has the same
 ingredients, color, density, and even taste
 mixed evenly throughout.
You can’t see the sugar crystals because
 they have broken up into molecules that
 mix with water molecules and food
 coloring.
Solutes and Solvents

The solute is the substance that
 dissolves.
The solvent is the substance that is doing
 the dissolving.
In sugar-water, sugar is the solute and
 water is the solvent.
What can dissolve in a liquid?

In a solution made with a liquid & a solid,
 the solid is the solute & the liquid is the
 solvent. Which is which in salt water?
What can dissolve in a liquid?

In a solution made with a liquid & a solid,
 the solid is the solute & the liquid is the
 solvent. Which is which in salt water?
Some solutions are gas dissolved in a
 liquid like carbonated soda in which
 carbon dioxide is dissolved in water.
What can dissolve in a liquid?
In a solution made with a liquid & a solid,
 the solid is the solute & the liquid is the
 solvent. Which is which in salt water?
Some solutions are gas dissolved in a
 liquid like carbonated soda in which
 carbon dioxide is dissolved in water.
Other solutions have a liquid dissolved in
 another liquid like food coloring in water
 with the solvent being the one present in a
 larger amount.
Are there solutions that do not contain a
liquid?
 Solutions can be mixtures of gases or
 even mixtures of solids.
  Air 78% N, 20% O, etc of other gases
  Sterling silver is a mixture of silver & copper, a
   solid solution or alloy is melted together
  Brass is copper & tin
How Substances Dissolve

A solid starts to dissolve at its surface.
 Water molecules are always moving and
 they are polar. Polar means they have a
 positive end and a negative end. Sugar is
 also polar so that the positive ends of the
 sugar molecules attract the negative ends
 of the water molecules. The water pulls
 the sugar into solution removing layer after
 layer of sugar until the crystal is dissolved.
How do liquid & gas solutions form?

It is similar but more complex because
 liquids and gases move much faster than
 solid particles.
The movement separates the solute
 particles and mixes them evenly in the
 solvent resulting in a homogeneous
 solution.
How do solids dissolve in other solids?

 Solids must be melted into liquids & then mixed
  together.
 In the liquid state, atoms move more freely to
  spread and form a homogeneous solution which
  stays even after cooling.
Rate of Dissolving:
 Can be increased by
  stirring or heating.
   Increases particle
    speed
 If the solute is a solid
  you can break it into
  smaller pieces.
   Increases surface area
Can you combine these methods?




                 o The rate of dissolving
                   increases with each
                   additional method you
                   use.
2 Solubility & Concentration

What You’ll Learn:
What solubility is
About the concentration of solutions
Three types of solutions
Factors that affect gas solutions
How much can dissolve?

Solubility is the greatest amount of solute
 that can dissolve in a specific amount of
 solvent at a given temperature.
How much can dissolve?

Solubility is the greatest amount of solute
 that can dissolve in a specific amount of
 solvent at a given temperature.
The difference of solubilities of solutes
 depends on the nature of the solute and
 the nature of the solvent.
How much solute is in a concentrated
solution?
 Concentration may be
  stated as a
  percentage by volume
  of the solute.
 A drink with 10
  percent fruit juice has
  10 mL of juice in 100
  mL of the drink.
Types of Solutions
                      You can use the
                       amount of solute
                       dissolved to describe
                       3 different types:
                       Saturated
                       Unsaturated
                       supersaturated
What is a saturated solution?
A saturated solution is one that contains
 all the solute it can hold at a given
 temperature.
If you increase the temp of the mixture,
 more solute can dissolve.
As shown in the following table, the
 solubility of solid solutes increases as the
 temperature of the liquid solvent
 increases.
                  Solubility of Compounds
                    in g/100 g of Water
compound              0°C       20°C        100°C
Copper(II) sulfate
                      23.1      32.0         114
Potassium
bromide
                      53.6      65.3         104
Potassium
chloride
                      28.0      34.0        56.3
Potassium nitrate
                      13.9      31.6         245
Sodium chlorate
                      79.6      95.9         204
Sodium chloride
                      35.7      35.9        39.2
Sucrose (sugar)
                      179.2     203.9       487.2
What is a solubility curve?
 Each line on the
  graph is a solubility
  curve for a
  substance.
 To find how much of a
  substance dissolves
  at a particular temp,
  find the temp on the
  x-axis & trace the line
  upward to the curve
  for that substance.
  What is an unsaturated solution?
                                           An unsaturated
                                            solution can dissolve
                                            more solute at a given
                                            temperature.
                                           An unsaturated
                                            solution can have any
                                            amount of copper (II)
                                            sulfate less than 32 g
                                            in 100 g of water at
                                            20°C.
www.sunflowerlearning.com/images/di.gif
 How can a solution be supersaturated?

 Honey is naturally a
  supersaturated
  solution.
 A supersaturated
  solution has more
  solute than a saturated
  solution at the same
  temperature. These
  solutions are unstable
  & may crystallize w/
  any addition of solute.
When do solutions give off energy?

Supersaturated sodium acetate solution
 becomes hot as sodium acetate
 crystallizes. Sometimes when bonds form,
 energy is given off in the form of heat.
Some heat packs are filled with a
 supersaturated solution that gives off heat
 as the solute crystallizes.
When do solutions give off energy?
Some solutes take energy from their
 surroundings to dissolve. As a result, the
 temperature of the solution is reduced.
Ammonium nitrate is an example. A cold
 pack has inner bags of water & ammonium
 nitrate. A solution forms when the inner
 bags are broken; energy is drawn from the
 water as the solution forms causing the
 temperature to drop thus the pack feels
 cool.
Solubility of Gases

Soda is a solution of carbon dioxide gas
 dissolved in flavored water. When you
 shake an open bottle of soda, it bubbles.
 Shaking or stirring a solution of a gas in a
 liquid allows more gas molecules to reach
 the surface of the liquid, where they
 escape into the air.
 How do pressure & temperature affect a
 gas dissolved in a liquid?
Soda is bottled under a great amount of
 pressure to force more gas to dissolve in the
 soda & to keep the gas in solution.
When you open the can, the pressure is
 released & bubbles of gas come out of
 solution.
Cooling a liquid increases the amount of gas
 that will dissolve in it (opposite of solids).
 Warm soda bubbles more than cold.
3 Particles in Solution

What You’ll Learn:
How some solutes form positively or
 negatively charged particles
How some solutions conduct electricity
How antifreeze works
Particles with a Charge
A particle with a charge is an ion. Ions
 are throughout your body in fluids helping
 nerve cells send messages controlling
 your muscles.
An electrolyte is a compound that
 produces solutions of ions that conduct
 electricity in water. Strong electrolytes,
 like NaCl dissolve completely into ions,
 conduct a strong electric current.
Particles with a Charge

Weak electrolytes, like acetic acid in
 vinegar, stay mainly as molecules when
 they dissolve in water, produce only a few
 ions and conduct current weakly.
Nonelectrolytes are substances that do
 not form ions in water and cannot conduct
 electricity. Organic molecules like sucrose
 (sugar) and ethyl alcohol are examples.
 How do ionic solutions form?
Ionization, the process of forming ions,
 happens when molecules are broken apart
 so that the atoms take on a charge.
  Polar molecules divide into ions, ex. HCl &
   waterH3O+ (hydrogen ion in water)
  The separation of ionic compounds into positive
   and negative ions is called dissociation. The next
   slide shows what happens to NaCl as it dissociates
   with H drawn to Cl & Na to O due to opposite
   charges.
Sodium & Chloride Ions Mixed w/ Water
Effects of Solute Particles
 All solute particles can affect physical properties
  of a solvent, such as freezing point & its boiling
  point.
How does antifreeze lower the freezing
point?
As a substance freezes, its particles
 arrange themselves in an orderly pattern.
 Solute particles interfere with this pattern
 making it harder for the solvent to freeze.
 A lower temperature is needed to freeze
 the solvent.
Why can some animals live in a cold
climate?

Caribou have substances in their bodies
 that keep their legs from freezing.
Fish also have a natural kind of antifreeze
 that keeps ice crystals from forming in
 their tissues.
Many insects have a similar chemical to
 protect them.
How can the boiling point of water be
raised?
Antifreeze also raises the boiling point of
 water by interfering with the evaporation of
 solvent particles.
More energy is needed for the solvent
 particles to escape from the liquid
 surfaces.
The more solute particles in the solution,
 the higher the boiling point of the solution
 will be.
How does antifreeze work in a car
radiator?
Solute particles block part of the surface
 so fewer water molecules can reach the
 surface & vaporize.
The solution cannot boil because the
 vapor pressure of the solution is lower
 than the vapor pressure of the solvent.
Added energy is required to raise the
 vapor pressure & make it boil.
4 Dissolving Without Water

What You’ll Learn:
What solutes do not dissolve in water
How polar and nonpolar solvents work in
 water
How to choose the right solvent for
 cleaning
When Water Won’t Work

There are some things, such as salad
 dressing with vinegar and oil, that water
 cannot dissolve.
Water molecules dissolve polar solutes but
 not most nonpolar ones without positive &
 negative areas.
How do nonpolar solutes behave?

Salad oils are made of large hydrocarbon
 molecules which share electrons in a
 nearly equal way. These nonpolar oil
 molecules are not attracted to polar water
 molecules. This is also why you have to
 shake oil and vinegar dressing to mix it
 before using it.
Why are alcohols special?
 Molecules of some
  substances have a
  polar end and a
  nonpolar end so they
  can form solutions
  with polar and
  nonpolar solutes.
 This is ethanol with
  an OH group that’s
  polar & the rest which   It can dissolve both nonpolar iodine
  is nonpolar.             and polar water.
Useful Nonpolar Molecules
Mineral oil can be used to remove candle
 wax from candleholders, bubble gum from
 some surfaces.
To remove wet paint or make it thinner use
 turpentine.
Gasoline is a solution of different
 hydrocarbons.
Dry cleaners use nonpolar solvents.
Remember “like dissolves like”.
When are nonpolar solvents not helpful?

Many nonpolar solvents are flammable or
 burn easily.
Some are toxic & should never be used in
 a closed room.
They evaporate readily so you must
 always have fresh air when using them.
How does soap work?
 Natural oils on your
  skin and hair keep
  them from drying out,
  but they also attract
  and hold dirt in a
  nonpolar mixture.
  You need to use soap
  with both polar and
  nonpolar properties to
  wash it away.
How does soap work?
 Soaps start out as
  large fatty acid
  molecules with long
  hydrocarbon ends
  that are nonpolar. A
  carboxylic acid group,
  COOH, is at the other
  end. Without the H
  atom, the end has a
  negative charge.
How does soap work?
 The ionic end of a
  soap molecule
  dissolves in water.
  The nonpolar end
  dissolves in oily dirt.
  Together the two
  ends of a soap
  molecule remove dirt
  so it can be rinsed
  away.
Polarity & Vitamins
                       Vitamin A from liver,
                        lettuce, cheese, eggs,
                        carrots, sweet
                        potatoes, and milk
                        can dissolve in body
                        fat because both are
                        nonpolar. Fat-soluble
                        vitamins can be very
                        harmful at high
                        concentrations.
 Polar vitamins, such
  as B & C dissolve in
  the water in your
  body. Excess
  vitamins wash away.
  Eat a healthful diet to
  avoid harmful
  overdose.

				
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