SOLUTIONS

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SOLUTIONS

• ICP
• What you need to know

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Heterogeneous mixturesWhat do these have in
common?

• Fruit salad
• Granite
• Mica
• Sand
• Clay
• Dirt
• Blood
• Milk

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A suspension is a heterogeneous mixture

• A mixture in which the particles are more or
  less evenly dispersed throughout a liquid or gas.
  

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Examples of suspensions

• Orange juice
• Muddy water
• Milk
• (a solution, colloid, and suspension)
• Blood
• (a solution, colloid, and suspension)
• Smoke

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The particles in a suspension

• Can be filtered out of the suspension
• Will often settle out if left undisturbed for a
  while

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Suspension have large particles.

• These particles are too large to dissolve, so
  they eventually settle out.

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Colloids

• Colloids have particle sizes that are smaller
  than in suspensions, but larger than in
  solutions.
• They are more stable than suspensions. They tend
  not to settle out.

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Examples of colloids

• Blood plasma (blood cells removed)
• Egg whites
• Fog

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The Polar Express
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An oil slick. There is an iridescent interface
between the polar, dense water and the nonpolar,
thin, and less dense oil layer.
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• What is a SOLUTE?
• The SOLUTE is the substance dissolved in the
  SOLVENT.
• In salt water
• salt is the SOLUTE
• water is the SOLVENT

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Some relatively polar solvents.

• Water
• Ethyl alcohol
• Rubbing alcohol (2-propanol)

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Water

• Water is considered a universal solvent because
  many different substances dissolve in water.

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Water is polar due to H-bonding
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LIKE DISSOLVES LIKE.

• Water and oil dont mix.
• Nonpolar solvents like oil
• tend to dissolve other nonpolars.
• Polar solvents like water tend to dissolve polar
  solutes and ionic compounds (salts).

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• Water will pull apart many ionic compounds
  (like table salt, NaCl, and other salts, like
  MgO, and other ionic compounds)
• See board

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Molarity

• Molarity is the number of moles of solute in a
  liter of solution.

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A one molar (1M) solution contains one liter of
solute per liter of solution.

• 1M 1 mole solute per liter of solution.
• The molar mass of NaCl is 58.6 grams/mole.
• How many grams of NaCl do I need to make two
  liters of a 1M NaCl solution?
• 58.6 grams NaCl x 1 mole x 2 liters
  117.2 grams NaCl
• mole liter

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SOLUBILITY

• Solubility reflects how much (mass) of a
  substance can dissolve in 100 mL of water.
• The main variable that affects how much of a
  substance can dissolve in a solvent is
  TEMPERATURE.
• As a rule, the higher the temperature, the
  greater the solubility. WHY?

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Interpreting graphs

• What two variables are shown in this graph?

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• At what temperature are the solubilities of
  sodium nitrate and potassium nitrate the same?

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• Which of the three salts is MOST sensitive to
  change in temperature?
• Which of the salts is LEAST sensitive to
  changes in temperature?

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• What is the solubility of KNO3 at 50oC?
• What is the solubility of NaNO3 at 20oC?

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• Which salt is most soluble in water at 10oC?
• Which salt is most soluble in water at 90oC?