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Solutions!

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Solutions! Heterogeneous Mixtures See visibly different regions Granite Dirt Cereals Oil & Vinegar See a boundary Ice cube in water Homogeneous Mixtures Particles ... – PowerPoint PPT presentation

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Title: Solutions!


1
Solutions!
2
Classification of Matter
3
Heterogeneous Mixtures
  • See visibly different regions
  • Granite
  • Dirt
  • Cereals
  • Oil Vinegar
  • See a boundary
  • Ice cube in water

4
Homogeneous Mixtures
  • Particles very small on atomic scale
  • Cant see particles
  • Cant sort particles
  • Cant get trapped by filter
  • Cant scatter light
  • Particles evenly distributed
  • Particles do not separate

5
CuSO4(aq)
6
Solution
  • Homogeneous mixture of 2 or more substances in a
    single physical state (phase)

7
Parts of a Solution
  • Solute dissolved substance
  • Solvent dispersing medium

8
Identify the solute and solvent in each picture
9
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10
Hints to identify solute solvent
  • Solute changes phase
  • substance have less of
  • Solvent maintains phase
  • substance have most of

11
Aqueous Solutions
  • Water is solvent
  • Transition metals form brightly colored solutions

12
Solutions occur in all 3 phases!
13
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14
CO2 in and out of water
Bubbles mean its a mixture not a solution!
15
Alloys
16
Soluble
  • Soluble capable of being dissolved
  • A substance that dissolves in another substance
    is soluble
  • in that substance

17
Insoluble
  • A substance that does not dissolve in another
    substance

18
Amounts that can dissolve
  • Solubility maximum amount of substance that
    will dissolve in given amount of another
    substance
  • LIMITS to amounts of most liquid/solid solutes
    that will dissolve in given solvent
  • Temperature and pressure affect solubility

19
Factors that affect the rate of dissolving
  • Rate of dissolving is different from amount that
    will dissolve!
  • Rate is how fast
  • factors influence rate of dissolving
  • Temperature
  • Stirring or Agitation
  • Surface Area of Solute
  • Amount of solute already dissolved

20
Dissolving
  • Dissolving is physical change
  • All physical chemical changes are accompanied
    by changes in energy

21
Equations for Dissolving
  • C6H12O6(s) H2O(l)? C6H12O6(aq)
  • NaCl(s)H2O(l) ? Na1(aq) Cl-1(aq)

22
Covalent substances dissolve to produce molecules
in solution
23
Ionic substances dissolve to produce ions in
solution
24
Solvation
  • Interaction between solvent molecules and solute
    particles
  • Solute particles surrounded by solvent particles
    in dissolving process
  • Solute particles may be ions, polar molecules, or
    nonpolar molecules
  • Solvent molecules may be polar or nonpolar

25
Hydration
  • Specific name for solvent-solute interaction when
    solvent is water

26
Hydration of chloride ion Also called
molecule-ion interaction
27
Solute-solvent interaction must be greater than
interaction between solute particles
for dissolving to occur
28
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29
Solubility
  • Amount solute that will dissolve in specific
    solvent at given TEMPERATURE and PRESSURE
  • Amount can be determined experimentally
  • Units
  • grams solute per 100 grams solvent

30
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31
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32
Why do you see bubbles form on the side of the
beaker as the water warms up? (Note its not
hot enough to boil)
33
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

34
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35
Types of Solutions
36
Electricity
  • What do you need to conduct electricity?

Mobile, charged particles!!!!
37
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

38
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39
Dilute vs. Concentrated
  • Tells relative amount of solute in solvent
  • Concentrated
  • large amounts of solute
  • Dilute
  • small amounts of solute

40
Which solution is most dilute? The most
concentrated? How do you know?
The stronger the color, the more concentrated the
solution
41
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42
Which solution is more concentrated? More
dilute? What can you say about the of solute
particles in pictures b and c?
43
Unsaturated Solution
  • Less solute than maximum amount that will
    dissolve at given temperature and pressure

44
Saturated Solution
  • No more solute will dissolve at given temperature
    pressure
  • Solubility amount of solute required to form a
    saturated solution

45
The solution is saturated when the solute stops
dissolving
46
Dynamic Equilibrium Saturated Solution
Microscopic level Rate of dissolving Rate of
recrystallization Macroscopic level No
apparent change
47
Supersaturated Solution
  • Contains more solute than saturated solution
  • VERY unstable
  • have to be clever to make these (need to use heat)

48
Testing for saturation
  • Toss crystal of solute into solution and see
    what happens

49
3 possible results
Unsaturated solution
  • Crystal dissolves
  • Crystal sinks to bottom of solution
  • Bam! Suddenly have lots of solid solute in
    beaker

Saturated solution
Supersaturated solution
50
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51
How do terms saturated, unsaturated
supersaturated fit in with the solubility curves?
  • Saturated solutions have maximum solute that will
    dissolve at given temperature
  • Any point on trace lines represent saturated
    solutions
  • All points above trace lines represent
  • supersaturated solutions
  • All points below trace lines represent
  • unsaturated solutions

52
Characterize points A, B, C, D with respect to
the KNO3 trace using the terms dilute
concentrated, saturated, unsaturated, or
supersaturated
A,C concentrated supersaturated
53
Summary of Dissolving
  • Occurs at surface of solid
  • Involves interaction between solute and solvent
  • Interaction is called solvation
  • If water is solvent, interaction is called
    hydration
  • Involves changes in energy

54
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55
Solubility Information
  • Often presented in graphs
  • Graph show number grams of substance that can
    dissolve in water between 0oC and 100oC
  • Trace line represents saturated solution
  • above trace line represents supersaturated
    solutions
  • below trace line represents unsaturated solutions

56
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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