Unit12L00 Solution Vocab R15.ppt

1. Solutions!

2. Classification of Matter
Matter
Pure
Substances
Mixtures
Homogeneous
Mixtures
Heterogeneous
Mixtures
Elements Compounds
Also called
solutions
Also called
suspensions

3. Solution
• A homogeneous mixture of 2
or more substances in a single
physical state (phase).
• Exist in all 3 phases.

4. Parts of a Solution
• Solute = dissolved substance.
• Solvent = dispersing medium.

5. Identify the solute
and solvent in each
picture.

6. Solute = ? Solvent = ?

7. Hints to identify solute & solvent
• Solute – changes phase,
substance you have less of
• Solvent – substance you have the
most of, maintains phase

8. Aqueous Solutions
• Water is the
solvent.
• Transition
metals form
brightly
colored
solutions.

9. Soluble
• Soluble – capable of being
dissolved.
• A substance that dissolves in
another substance is soluble in
that substance.

10. Insoluble
• A substance that does not
dissolve in another substance.

11. Amounts that can dissolve
• Solubility = maximum amount of 1
substance that will dissolve in a given
amount of another substance.
• LIMITS to the amounts of most liquid
or solid solutes that will dissolve in a
given solvent.
• Temperature and pressure can affect
solubility.

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

13. Dissolving
• Dissolving is a physical change.
• All physical & chemical changes
are accompanied by changes in
energy.

14. Equations for Dissolving
C6H12O6(s)  C6H12O6(aq)
NaCl(s)  Na+(aq) + Cl-(aq)

15. source
Covalent substances dissolve to
produce molecules in solution.

16. Ionic substances dissolve to
produce ions in solution.
Movie: Dissolution of NaCl

18. Solvation
• Interaction between the solvent
molecules and the solute particles.
Solute particles are surrounded by
solvent particles in the dissolving
process.
• Solute particles may be ions, polar
molecules, or nonpolar molecules.
• Solvent molecules may be polar or
nonpolar.

19. Hydration
• Specific name for the solvent-
solute interaction when the
solvent is water.

20. Hydration of
chloride ion.
Also called a
molecule-ion
interaction.

21. The solute-
solvent
interaction must
be greater than
the interaction
between solute
particles for
dissolving to
occur.
Molecule-ion interaction

22. Solubility
• Amount of solute that will dissolve in
a specific solvent at a given
TEMPERATURE and PRESSURE.
• Determined experimentally.
• Units:
grams solute per 100 grams solvent

23. Solubility Curves of Selected Solids
Solubility
traces for
most but not
all solids have
+’ve slopes.
The hotter the
solvent, the
more solute
dissolves.

24. Why do we heat the water up when
making rock candy?

25. Solubility Curves of Selected Gases
Solubility
traces for all
gases have
–’ve slopes.
Why do fish like cold water?

26. Why do you see
bubbles form on
the side of the
beaker as the
water warms up?
(It’s not hot
enough to boil.)

27. Vocabulary Interlude
• Miscible: two liquids that will mix in
any amounts.
–Water and ethanol are miscible in all
proportions.
• Immiscible: Liquids that cannot mix
–Oil and water are immiscible.

28. Oil & H2O are immiscible.

29. Types of Solutions
Matter
Pure Substances Mixtures
Homogeneous
Mixtures =
Solutions
Heterogeneous
Mixtures
Elements Compounds
Conduct current
Nonconductor

30. Electricity
• What do you need to conduct
electricity?
Mobile charged particles!!!!

31. Vocabulary Interlude
• Electrolyte: A substance that dissolves in
water to form a solution that conducts
electricity. (There are ions in the solution.)
• Nonelectrolyte: A substance that
dissolves in water to form a solution that
does not conduct electricity. (There are
neutral molecules in solution.)

32. Electrolyte vs. Nonelectrolyte
Which solution conducts a current?

33. Dilute vs. Concentrated
• Tell you relative amount of solute in
solvent.
• Concentrated – relatively large
amounts of solute.
• Dilute – relatively small amounts
of solute.

34. Which solution
is the most
dilute? The
most
concentrated?
How do you
know?
The stronger the color, the more
concentrated the solution.

36. Which solution
is more
concentrated?
More dilute?
What can you
say about the
number of
solute particles
in pictures b and
c? It’s the same!

37. Unsaturated Solution
• Has less solute than the
maximum amount that will
dissolve at that temperature and
pressure.

38. Saturated Solution
• No more solute will dissolve in it
at that temperature & pressure.
• Solubility = amount of solute
required to form a saturated
solution.

39. The solution is saturated when the
solute stops dissolving.

40. Dynamic Equilibrium = Saturated Solution
Microscopic
level: Rate of
dissolving =
Rate of
recrystallization.
Macroscopic
level: No
apparent
change.

41. Supersaturated Solution
• Contains more solute than a
saturated solution.
• VERY unstable.
• Have to be clever to make them
up.
Sodium Acetate Solution
Heat Pack
Temperature

43. Testing for saturation:
• Throw a crystal of the solute into
the solution and see what
happens.

44. 3 possible results:
• Crystal dissolves
• No apparent change in crystal
• Bam! Suddenly have lots of solid
solute in beaker.
Unsaturated
solution.
Saturated
solution.
Supersaturated
solution.

45. What kind of solution was this?

46. How do the terms saturated,
unsaturated & supersaturated fit
in with the solubility curves?
• Saturated solutions have maximum solute that
will dissolve at that temperature. Points on
traces represent saturated solutions.
• All points above a trace represent
supersaturated solutions of that solute.
• All points below a trace represent unsaturated
solutions of that solute.

47. A
B
C
D
Characterize points
A, B, C, D with
respect to KNO3
trace using the
terms dilute &
concentrated, and
saturated,
unsaturated, or
supersaturated.
A = concentrated &
supersaturated.
D = dilute & unsaturated.

48. Summary of Dissolving
• Occurs at the surface of the solid.
• Involves an interaction between the
solute and the solvent.
• Interaction is called “solvation.”
• If water is the solvent, the interaction
is called “hydration.”
• Involves changes in energy.

50. Solubility Information
• Often presented in graphs
• Show the number of grams of a substance that
can be dissolved in water between 0oC and
100oC.
• Each trace represents a saturated solution.
– The space above each trace represents
supersaturated solutions.
– The space below each trace represents unsaturated
solutions.

51. Solubility Graphs
• Some traces have positive slopes; some
are negative.
• Most solids have a positive slope – the
hotter the water, the more solute
dissolves.
• All gases have a negative slope – the
hotter the water, the less gas dissolves.
– The colder the water, the more gas dissolves.