Solutions - Polk School District

Solutions
Chemistry
Mr. Moss
RHS
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SC7. Students will characterize the properties that
describe solutions and the nature of acids and bases.
 a. Explain the process of dissolving in terms of
solute/solvent interactions:
 Observe factors that effect the rate at which a solute
dissolves in a specific solvent,
 Express concentrations as molarities,
 Prepare and properly label solutions of specified molar
concentration,
 Relate molality to colligative properties.
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In this unit, we will be looking at
different types of mixtures, all of
which are classified by the size of
the particles in them.
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What is a Solution?
 A homogeneous mixture containing two or more
substances called the solute and the solvent.
 The solute is the part that is dissolved.
 The solvent is the dissolving medium.
 Has a constant composition throughout.
 Always has a single phase.
 You cannot distinguish the solute from the solvent
when you look at a solution.
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Mixtures
 A combination of two or more substances that are
not chemically combined.
 A blend of tow or more kinds of matter, each of
which retains its own identity and properties.
 Two types:
 Homogeneous (same proportions throughout)
 Heterogeneous (not uniform throughout)
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Mixtures
Homogeneous
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Heterogeneous
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Brainstorm
Activity
Brainstorm a list of
common solutions with
two other people
sitting NEAR you.
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How can solutions exist?
 Solutions can exist as
 Solids
 Liquids
 Gases
 Depends on the state of the solvent.
 Will be in a single phase.
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Components of a Solution
 Two main components:
 Solvent
 The dissolving medium.
 The component in the largest quantity.
 Solute
 The substance dissolved.
 The component in the lesser quantity.
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Example
 If I take a teaspoon of salt and put it into a bucket of
water, I have made an unsaturated saltwater solution.
 The salt is the solute.
 The water is the solvent.
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Common Solvents





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Water
Kerosene
Mineral Oil
Turpentine
Paint Remover
Nail Polish Remover
 Acetone
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Types of Solution Systems
System
Example
Gas-gas
Air is a mixture of nitrogen, oxygen, and argon gases.
Gas-liquid
Carbonated beverages contain carbon dioxide gas in
solution.
Liquid-gas
Moist air contains water droplets in air.
Liquid-liquid
Vinegar contains acetic acid and water.
Solid-liquid
Sweetened powder drink contains sugar and other solid
ingredients in water.
Solid-solid
Steel is an alloy of iron containing carbon.
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IMPORTANT!
Water is
the most
common
solvent.
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Do all combinations of substances
form solutions?
Nope
The solute must be soluble in
the particular solvent.
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Suspensions
 If the particles in a solvent are so large that they
settle out unless the mixture is constantly stirred or
agitated.
 Jar of muddy water
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Colloids
 Particles that are intermediate in size between those
in solutions and suspensions form mixtures known as
colloidal dispersions, or simply colloids.
 1 nm and 1000 nm in diameter.
 Emulsion and foam are familiar terms.
 Mayonnaise
 Emulsion of oil drops in water.
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Solubility
 The ability of a solute to dissolve in a solvent.
 NaCl is soluble in water.
 Sand is insoluble in water.
 The maximum amount of solute that will dissolve in a
given solvent at a particular temperature and
pressure.
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Electrolytes vs. Nonelectrolytes
 Solutes that dissolve are classified according to
whether they yield molecules or ions in solution.
 Ionic compounds separate into positive and negative
ions.
 Allows for an electric current to pass through the
solution.
 A substance that dissolves in water to give a solution
that conducts electric current is called an Electrolyte.
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Electrolyte vs. Nonelctrolyte
 If a solution contains a neutral solute molecule, it will
not conduct electric current.
 A substance that dissolves in water to give a solution
that does not conduct an electric current is called a
nonelectrolyte.
 Sugar
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Factors that affect dissolving rate
 3 factor will affect how fast a solute dissolves:
 Temperature
 Surface area
 Agitation
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Is it Dilute or Concentrated?
 Concentration is a measure of the mass of solute
dissolved in a certain volume of solvent.
 The more solute dissolved, the greater the
concentration.
 Three KEY terms:
 Unsaturated
 Saturated
 Supersaturated
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Unsaturated
 A solution that contains LESS dissolved solute for a
given amount of solvent at a specific temperature
and pressure.
 More solute can be dissolved.
 It “ain’t” full yet.
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Saturated
 A solution that contains the MAXIMUM amount of
dissolved solute for a given amount of solvent at a
specific temperature and pressure.
 It is full!
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Supersaturated
 Contains more dissolved solute than a saturated
solution at the same temperature.
 Formed at high temperature and cooled slowly.
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Solubility
 Usually given as grams of solute per 100 grams of
solvent or per 100 mL of solvent at a given
temperature.
 Rate at which a solid dissolves is unrelated to its
solubility at that temperature.
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Solubility Curve
 A graph of solubility as
temperature increases.
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