Solution Chemistry and Solubility

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Solution Chemistry and Solubility

• 12ADemonstrate and explain effects of
  temperature and the nature of solid solutes on
  the solubility of solids
• 13ACompare unsaturated, saturated, and
  supersaturated solutions
• 13BInterpret relationships among ionic and
  covalent compounds, electrical conductivity, and
  colligative properties of water

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Review

• Elementsubstance that cannot be broken down into
  simpler substances (periodic table)
• Compounda substance made of atoms of more than
  one element bound together (H2O, CO2, NaCl)
• Mixturea combination of more than one pure
  substance (Salt water, Powerade, Salad)

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Mixture Review

• Mixturea physical blend of two or more
  substances
• Heterogeneous mixtureone that is not uniform in
  composition
• Homogeneous mixtureone that has a completely
  uniform composition

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Mixture Review
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Mixture REVIEW

• You can separate mixtures by PHYSICAL means
• Distillation
• Separation
• Chromatography

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Type Particle size Settle upon standing Tyndall effect (Scatter light)
Solutions Homo-geneous 0.01-1 nm No no
Colloid Hetero-geneous 1-1000 nm No Yes
Suspension Hetero-geneous Greater than 1000 nm Yes sometimes
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Solution Chemistry

• Solutiona homogeneous mixture
• Solutedissolved particles in a solution
• Solventthe dissolving medium in a solution
  (usually water, the universal solvent)

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Kool-Aid Solution

• Kool-Aid Juice is the SOLUTION
• Kool-Aid powder and Sugar are the SOLUTES
• Water is the SOLVENT

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Soluble vs. Insoluble

• Solubledissolves completely so that solution
  looks transparent (free of any floating particles
• Insolubledoes not dissolve completely solution
  is cloudy

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How does dissolving takes place?

• What happens when salt is dissolved in water?
• NaCl ? Na Cl-

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Complete the dissociation of the following salts

• KCl ?
• MgCl2?
• AlCl3?
• MgF2?

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Solution Chemistry

• Electrolytescompounds that conduct an electric
  current
• ALL ionic compounds NaCl, CuSO4, NaOH
• NonelectrolytesCompounds that do not conduct an
  electric current in either aqueous solution or
  the molten state
• Many molecular compounds carbon, sugar, alcohol

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Electrolytes vs. Nonelectrolytes
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Electrolytes vs. Nonelectrolytes

• Some very polar molecular compounds are
  nonelectrolytes in pure state but become
  electrolytes when dissolved in water
• NH3(g) H2O(l) ? NH4(aq) OH-(aq)

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Electrolytes vs. Nonelectrolytes

• Weak Electrolyteonly a fraction of the solute
  exists as ions
• Strong Electrolytealmost all the solute exists
  as separate ions

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Strong electrolyte in solution.
Weak Electrolyte in solution.
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Electrolytes vs. Nonelectrolytes

• STRONG ELECTROLYTES
• Strong acids (HCl, H2SO4, HNO3)
• Strong bases (NaOH, KOH)
• WEAK ELECTROLYTES
• Weak acids (Vinegar, acetic acid, CH3COOH)
• Weak bases (Ammonia, NH3)
• NONELECTROLYTES
• Molecular compounds
• Nonmetal bonded to nonmetal

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Electrolytes vs. Nonelectrolytes

• More ions in solutions, the more conductivity
• Which salt would give more ions NaCl or MgCl2?
• So, which will conduct electricity more/be a
  better electrolyte?
• Look back at the dissociation reactions and
  determine the better electrolyte.

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Solutions are homogeneous mixtures that could be
solid, liquid, or gaseous
Gas Gas Oxygen in nitrogen
Gas Liquid CO2 in water
Liquid Gas Water in air
Liquid Liquid Alcohol in water
Liquid Solid Mercury in silver and tin (dental amalgam)
Solid Liquid Sugar in water
Solid Solid Copper in nickel (alloys)
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Solubility

• Solubilitythe amount that dissolves in a given
  quantity of a solvent at a given temperature to
  produce a saturated solution.
• Solubility is often expressed in grams of solute
  per 100g of solvent

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Water and Solubility?

• REMEMBER water is a POLAR molecule
• Polar means electrons are not spread evenly
  throughout the molecule
• Polar molecules dissolve polar molecules
• Water can dissolve ammonia
• Nonpolar molecules dissolve nonpolar molecules
• Octane (gasoline) can dissolve CO2
• LIKE DISSOLVES LIKE!!!!

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Solution Concentration

• Concentrationthe quantity of solute dissolved in
  a given quantity of solution
• Three ways to describe a solution
• Unsaturated solution
• Saturated solution
• Supersaturated solution

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Solubility

• Unsaturateda solution that contains less solute
  than it can hold in a given solvent
• Saturateda solution that contains the maximum
  amount of solute for a given amount of solvent
  at a constant temperature
• Supersaturateda solution that contains more
  solute than it can theoretically hold at a given
  temperature crystals form

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Solubility

• Two liquids are said to be MISCIBLE if they
  dissolve in each other
• Water and ethanol dissolve in each other
• Liquids that are insoluble in each other are
  IMMISCIBLE.
• Oil and water do no dissolve in each other

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MISCIBLE Water and alcohol
IMMISCIBLE Water and oil
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Gas Solubility

• Henrys Lawas the pressure of the gas above the
  liquid increases, solubility of the gas increases
  and vice versa

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Gas Solubility

• Henrys Law
• S solubility
• P Pressure

S1 S2 P1 P2

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Gas Solubility

• EXAMPLES
• Ears Popping
• Underwater Diving (the bends)
• Airplane taking off or landing

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Factors Affecting Rate of Dissolving

• SURFACE AREA
• Solutes with larger surface area dissolves faster
• Smaller pieces dissolve faster than larger pieces

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Factors Affecting Rate of Dissolving

• STIRRING
• Stirring or shaking a solution helps the solute
  dissolve faster
• Stirring or shaking moves dissolved sugar away
  from undissolved sugar crystals

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Factors Affecting Rate of Dissolving

• TEMPERATURE
• Solutes dissolve faster when the solvent is hot
• When substance is heated, particles move faster
  causing more collisions between particles

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Factors Affecting Solubility

• Things that dissolve in water are called SOLUBLE
• Things that do not dissolve in water are called
  INSOLUBLE

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Solubility Curves

• Solubility curves (graphs) give the solubility
  and temperature of a saturated solution.
• Solubility is on y-axis
• Temperature (C) is on x-axis

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Solubility Curve
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Solubility Curves

• SATURATED solution is ON line or curve
• UNSATURATED solution is BELOW line or curve
• SUPERSATURATED solution is above line or curve