Monday, Feb. 17th:

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Monday, Feb. 17th A DayTuesday, Feb. 18th
B DayAgenda

• Chapter 12 Tests
• Begin Chapter 13 Solutions
• Section 13.1 What is a Solution?
• Solution, suspension, solvent, solute, colloid
• Demos
• In-Class Section 13.1 review, pg. 459 1-8
• ACT Practice
• Homework Concept Review What is a Solution?
• Next time Quiz over this section,
• Lab Write-Up and Lab

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Ch. 12 TestsGases
Class Avg. Score (out of 60) Avg. Percent
3A
4B
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Mixtures

• Mixtures can be either heterogeneous or
  homogeneous.
• The particles of a heterogeneous mixture are
  large enough to see under a microscope.
• Example tomato soup
• In a homogeneous mixture, however, the particles
  are molecule-sized, so the mixture appears
  uniform, even under a microscope.
• Example gasoline
• A solution is a homogeneous mixture of two or
  more substances uniformly dispersed throughout a
  single phase.

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Suspensions are Temporary Heterogeneous Mixtures

• A suspension is a mixture in which particles of a
  material are more or less evenly dispersed
  throughout a liquid or gas.
• In a suspension, the particles may remain mixed
  with the liquid while the liquid is being
  stirred, but later settle to the bottom.

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Clay particles suspended in water form a
suspension.
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Solution is a Broad Term

• Any mixture that is homogeneous on a microscopic
  level is a solution. According to that
  definition, air is a gaseous solution.
• A homogeneous liquid mixture has one main
  componenta liquidas well as one or more
  additional ingredients, usually present in
  smaller amounts.

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Solvent

• The primary ingredient in a solution is called
  the solvent.
• Solvent in a solution, the substance in which
  the solute is dissolved.
• Water is the most common solvent and is sometimes
  called the universal solvent.
• Water is a unique solvent because so many
  substances can dissolve in it.
• Solutions in which water is the solvent are
  called aqueous solutions.

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Solute

• The other ingredients in a solution are called
  the solutes and are said to be dissolved in the
  solvent.
• Solute in a solution, the substance that is
  dissolved in the solvent.
• Example In a salt water solution, sodium
  chloride is the solute and water is the solvent.

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Solution is a Broad Term

• Another type of solution involves one solid mixed
  with another solid.
• A solid or liquid mixture of 2 or more metals is
  called an alloy.
• Examples include solid alloys, such as brass,
  bronze, and steel.

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Particle Models for Gold and Gold Alloy
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Colloids Are Stable Heterogeneous Mixtures

• A colloid is a mixture consisting of tiny
  particles that are intermediate in size between
  those in solutions and those in suspensions and
  that are suspended in a liquid, solid,
• or gas.
• The particles in a colloid usually
• have an electric charge.
• These charged particles repel each other, so they
  do not collect into larger particles that would
  settle out.

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Milk is a Collloid

• Milk appears to be homogeneous. But under a
  microscope you see that milk contains globules of
  fat and small lumps of the protein casein
  dispersed in a liquid called whey. Milk is a
  colloid because the particles of casein do not
  settle out after standing.

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Separating Mixtures

• Mixtures are separated based on their physical
  properties.
• Mixtures may be separated
• by decanting (pouring off the liquid)
• with a centrifuge
• filtering
• evaporation

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Chromatography Separates by Differences in
Attraction

• Chromatography separates components of a mixture
  based on how quickly molecules dissolved in a
  mobile phase solvent move along a solid phase.
• Paper chromatography is a
• powerful technique for separating
• solutions.
• Dyes that are attracted more
• strongly to the paper travel more
• slowly along the paper.

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Distillation Separates by Differences in Boiling
Point

• If the boiling points of the components are
  different, distillation can separate them based
  on their boiling points.
• As one component reaches its boiling point, it
  evaporates from the mixture and is allowed to
  cool and condense. This is called a distillate.
• This process continues until all the desired
  components have been separated from the mixture.

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Fractional Distillation

• Distillation is used in the petroleum industry to
  separate crude oil into fractions according to
  their boiling points.

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Demonstration Solutions

• What happens when each of the following materials
  is added to 200 mL of water?
• Sucrose
• Potato starch
• Silicon dioxide
• Food coloring
• Vegetable oil

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In-Class/Homework

• In-Class Assignment
• Section 13.1 review, pg. 459 1-8
• When you finish, pick up the ACT practice
  questions. (Heat Capacity/Phase Changes)
• Homework
• Concept Review What is a Solution?
• Next time
• Quiz over this section
• Chromatography Lab Write-up
• and Lab