Solutions: More Vocab

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SolutionsMore Vocab
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Soluble

• Soluble capable of being dissolved
• A substance that dissolves in another substance
  is said to be soluble in that substance

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Insoluble

• A substance that does not dissolve in another
  substance

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• Solubility maximum amount substance that
  dissolves in given amount of another substance
• LIMIT to amount solute that dissolves in given
  amount solvent
• affected by temperature and pressure

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• Rate of dissolving is different from amount that
  will dissolve!
• Rate is how fast
• Amount is how much

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Factors that affect the rate of dissolving

• temperature
• stirring or agitation
• amount of surface area of solute
• amount of solute already dissolved

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Dissolving

• Dissolving is physical change
• Reminder all physical chemical changes
  accompanied by change in energy

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• dissolved covalent substances
• produce molecules in solution
• C6H12O6(s) H2O(l)? C6H12O6(aq)

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dissolved ionic substances produce ions in
solution
NaCl(s)H2O(l) ? Na1(aq) Cl-1(aq)
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Solvation

• Interaction between solvent molecules solute
  particles
• solute particles surrounded by solvent particles
  during dissolving process
• Solute particles may be
• ions
• polar molecules
• non-polar molecules
• Solvent molecules may be
• polar
• non-polar

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Hydration

• describes solvent-solute interaction when
  solvent is water

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Hydration of chloride ion Also called
molecule-ion interaction
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Solute-solvent interaction must be greater than
interaction between solute particles
for dissolving to occur
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Solubility

• amount solute dissolved in specific solvent at
  given TEMPERATURE and PRESSURE
• units
• grams solute per 100 grams solvent

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Vocabulary Interlude

• Miscible two liquids that WILL MIX
• together in any amounts
• Water and ethanol are miscible in all proportions
• Immiscible liquids that will NOT MIX
• Oil and water are immiscible

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Types of Solutions
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Electricity

• What do you need to conduct electricity?

Mobile, positively charged particles!!!!
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Vocabulary Interlude

• Electrolyte
• substance that dissolves in water to form
  solution that conducts electricity
• ions in solution
• Nonelectrolyte
• substance that dissolves in water to form
  solution that does not conduct electricity
• neutral molecules in solution

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Dilute vs. Concentrated

• Concentrated
• large amounts of solute
• Dilute
• small amounts of solute

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Which solution is most dilute? The most
concentrated? How can you tell?
The stronger the color, the more concentrated the
solution
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To dilute a Solution add MORE solvent
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Which solution is more concentrated? More
dilute? What can you say about the of solute
particles in pictures b and c?
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Unsaturated Solution

• Less than maximum amount solute that will
  dissolve at given T and P

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Saturated Solution

• No more solute will dissolve at given T P
• Solubility amount solute required to form
  saturated solution

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The solution is saturated when the solute stops
dissolving
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Dynamic Equilibrium in Saturated Solution
Microscopic level Rate dissolving Rate
recrystallization Macroscopic level No
apparent change
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Supersaturated Solution

• Contains more solute than saturated solution
• VERY unstable
• have to be clever to make these (need to use heat)

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Testing for saturation

• add additional crystal of solute into solution
  and see what happens

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3 possible results
Unsaturated solution

• Crystal dissolves
• Crystal sinks to bottom of solution
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  Bam! Suddenly have
  
• lots of solid
  solute
• in beaker

Saturated solution
Supersaturated solution
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How do terms saturated, unsaturated
supersaturated fit in with the solubility
curves?
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• Saturated solns
• any point on trace line
• (max solute dissolved)
• Supersaturated solns
• all points above trace lines (more than max)
• Unsaturated solutions
• all points below trace lines (less than max)

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Characterize points A, B, C, D with respect to
KNO3 trace line (dilute, concentrated,
saturated, unsaturated, or supersaturated)
A,C concentrated supersaturated Bconcentrat
ed saturated
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Solubility Graphs

• Traces have positive or negative slopes
• Most solids have positive slope
• the hotter the water, the more solute dissolves
• The colder the water, the less solute dissolves
• All gases have negative slope
• the hotter the water, the less gas dissolves
• The colder the water, the more gas dissolves

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Summary of Dissolving

• Occurs at surface of solid
• Interaction between solute solvent
• Interaction called solvation
• Interaction called hydration (if solvent is
  H2O)
• Involves change in energy

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