Classification of Matter and Solutions Notes Part 1

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Classification of Matter and Solutions Notes Part
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I. Classification of Matter

• Matter
• Can it be physically separated?
• Yes
  No
• Mixtures Pure Substances
• Is the composition uniform? Can it be decomposed
  by an ordinary chemical reaction?
• Yes No Yes
  No
• Homogeneous Heterogeneous Compounds
  Elements
• Mixtures Mixtures (water, sodium
  (gold, oxygen,
• (Solutions) (Suspensions chloride, sucrose)
  carbon)
• (air, sugar water, or Colliods)
• salt water) (granite, wood,
• muddy water)

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• Mixtures matter that can be physically separated
  into component parts.
• a. homogeneous mixture has uniform composition
  also called a solution
• b. heterogeneous mixture does not have a
  uniform composition suspensions or colloids

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• Pure Substances when component parts of a
  mixture can no longer be physically separated
  into simpler substances. Pure substances are
  either compounds or elements.
• a. Compounds can be decomposed by a chemical
  change.
• b. Elements cannot be decomposed by a chemical
  change.

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II. Types of Mixtures (Solutions, Suspensions,
and Colloids) Table 13-3 page 398

• 1. Solution (homogeneous mixture)- any substance
  (solid, liquid, gas) that is evenly dispersed
  throughout another substance. Ex sugar water,
  salt water (do not scatter light)
• Components of a Solution
• 1. Solute substance dissolved
• 2. Solvent substance that does the dissolving
  (water is the universal solvent)

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• 2. Suspensions (heterogeneous mixtures)
  particles in a solvent are so large that they
  settle out unless the mixture is constantly
  stirred Ex muddy water, vegetable soup, page
  398 (may scatter light, but are transparent)

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• 3. Colloids (heterogeneous mixtures) particles
  are intermediate in size between those in
  solutions and suspensions. Example After large
  soil particles settle out of muddy water the
  water is often still cloudy because colloidal
  particles remain dispersed in the water. Ex
  milk, mayonnaise , page 398 (do scatter light
  Tyndall Effect)

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• III. The Solution Process (Solvation)
• Solvation is the process by which a solute
  dissolves in a solvent.
• Miscible when solutes and solvents are soluble
  in each other (solvation occurs)
• Immiscible when solutes and solvents are not
  soluble in each other (solvation does not occur)
• Aqueous solutions solvent is water.

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IV. Like Dissolves Like

• We dont always use water as the solvent!
  Solutions can be made from various substances a
  rule of thumb to follow when trying to determine
  if two substances will form a solution is like
  dissolves like.

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• Solubility the maximum amount of a substance
  that will dissolve in a solvent (at a specific
  temperature)
• According to solubility, solutions can be either
• unsaturated a solution that is able to dissolve
  more solute (not enough)
• saturated a solution that cannot dissolve any
  more solute (just enough)

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• supersaturated a solution that contains more
  solute than can be dissolved (too much!!)
• The solubility of substances varies widely. For
  example 0.189 grams of Ca(OH)2 dissolves in 100
  grams of water at 0?C. 122 grams of AgNO3
  dissolves in 100 grams of water at 0?C. (page
  404 in your book)

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VI. Factors Effecting Rate and Solubility

• Factors Effecting Rate
• 1. Agitation stirring or mixing the solution
  will increase the rate or how fast the solute
  dissolves, but it will not change how much solute
  can be dissolved. If you add 35.9 grams of salt
  to water (at 20?C) it will all eventually
  dissolve, but if you stir the solution it will
  dissolve much quicker. (As you stir the
  particles are constantly being moved, allowing
  for interactions between solute and solvent to
  occur more quickly.)

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• Surface Area increasing the surface area of the
  solute will increase the rate or how fast the
  solute dissolves, but it will not change how much
  solute can be dissolved.
• 3. Temperature increasing temperature will
  increase the rate or how fast the solute
  dissolves in the solvent. (As temperature
  increases the particles begin to move faster and
  faster and collide with more particles quicker,
  which means the solute and solvent particles have
  an increased chance of coming into contact with
  each other.)

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B. Factors Effecting Solubility

• 1. Increasing Temperature - solubility of a
  solid solute in a liquid solvent generally
  increases with an increase in temperature. At
  20?C 35.9 grams of salt will dissolve in 100
  grams of water, but at 100 ?C 39.2 grams of salt
  will dissolve in 100 grams of water!

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• 2. Decreasing Temperature-increases the
  solubility of a gaseous solute in a liquid
  solvent. What would you rather drink, a hot coke
  or a cold coke?

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• 3. Pressure The solubility of a gas increases
  as the pressure of the gas above the liquid
  increases. Carbonated drinks have CO2 dissolved
  in them. They are also bottled under a high
  pressure of CO2, which forces the CO2 into
  solution. When the bottle is opened, the pressure
  above the solution decreases, and bubbles of CO2
  form in the liquid, then escape. Eventually, most
  of the CO2 escapes and the drink becomes flat.

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• Henrys Law- At a given temperature, the
  solubility, S, of a gas in a liquid is directly
  proportional to the pressure, P, of the gas above
  the liquid.
• S1 S2
• P1 P2

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VII. Electrolyte VS Nonelectrolyte

• 1. Electrolyte compounds that conduct an
  electric current in an aqueous solution OR in the
  molten state. An electrolyte solution contains
  charged particles (ions), which can move. Any
  salt dissolved in water is an electrolyte NaCl,
  KI, etc. Some polar molecules also conduct
  electricity (most acids are electrolytes because
  H is the only nonmetal that has a charge).

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Types of Electrolytes

• 1. Strong electrolytes a large portion of the
  solute exists as ions
• a. aqueous solutions of all ionic compounds
• b. strong acids have at least 2 oxygens per
  hydrogen (H2SO4, HNO3)
• c. strong bases these are hydroxides from
  Group I and II, except Be. (NaOH, CsOH, etc)

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• 2. Weak electrolytes these are solutions in
  which only a small portion of the solute exists
  as ions
• a. weak acids
• -all binary acids HF, H2S, etc
• -weak acids that have less than 2 oxygen's per
  hydrogen
• b. weak bases hydroxides of everything else
  not in Group I or II, including Be(OH)2

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• 2. Non-Electrolytes- compounds that do NOT
  conduct electricity in either aqueous solution or
  when melted
• distilled water
• gases
• molecular compounds (2 nonmetals)
• organic compounds alcohols, sugars, etc.
  anything containing a Carbon

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• Practice Problems Tell whether each of the
  following aqueous solutions would be a STRONG,
  WEAK, or NON electrolyte.
• NaCl 2. CH3Br (l) 3. HMnO4
• HC2H3O2 5. LiOH 6. HC6H7O6
• 7. CO2 (l) 8. HF

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• VIII. Concentration the concentration of a
  solution is a measure of the amount of solute in
  a given amount of solvent or solution.