1. Solutions and mixtures

3. Quick Review An element is a substance made up of atoms of one kind.
A molecule is formed when atoms of the same elements combine.
Two atoms of oxygen combine to form a molecule of oxygen [O2]
A compound is formed when atoms or molecules of different elements combine chemically.
Hydrogen and oxygen are combined in a fixed proportion of 2:1 to form the compound water [H2O].
Mixtures are two or more substances that are mixed together but not chemically joined.

4. Pure vs. Mix A pure substance:
cannot be separated into 2 or more substances by physical means
has uniform composition throughout the whole sample
A mixture:
can be separated into 2 or more substances by physical or mechanical means
displays the properties of the pure substances making it up
its composition can be varied by changing the proportion of pure substances making it up
heterogeneous substances, ones with non-uniform composition throughout the sample, are always mixtures

5. Mixtures
When a mixture’s components are easily recognizable, such as pizza, it is called a heterogeneous mixture.
In a homogeneous mixture such as chocolate milk, the component particles cannot be distinguished, even though they still retain their original properties.

6. More on mixtures
Homogeneous – particles distributed evenly; the same throughout
Heterogeneous – PARTICLES not evenly distributed; NOT THE SAME throughout

7. Type of Mixture
Example
gas in gas
The atmosphere is a mixture of gases, mostly nitrogen and oxygen.
liquid in liquid
Wine is a mixture of mostly ethanol and water.
solid in solid
Alloys, such as brass, are made up of a mixture of metals.
gas in liquid
Soft drinks, such as cola, are mixtures of mainly carbon dioxide gas and water.
solid in liquid
Sea Water is a mixture of salts dissolved in water.
solid in gas
Smoke is mixture of tiny solid particles in atmospheric gases.

8. Solution aka Homogenous Mixture
Solutions are composed of one or many solute(s) and only 1 solvent
Solute: substance that dissolves into the solvent
Solvent: substance that dissolves the solute(s)

9. A solution can exist in any of the 3 states of matter: (solid, liquid or gas) Solid Solutions ex: brass = copper + zinc This is called an alloy. (solvent) (solute) Gas Solutions ex: air = nitrogen + oxygen + argon + carbon dioxide (solvent) (solutes) Liquid Solutions ex: vinegar = acetic acid + water (solvent) (solute)

10. Transformation of Matter
Physical vs. Chemical Changes

11. What do you have left when
you melt an ice cube?
Physical changes are those changes that do not result in the production of a new substance. 
Chemical changes are changes that result in the production of another substance.

12. Physical Changes
Does not result in the formation of a new substance: the particles remain the same
Physical changes are reversible
Alters only non-characteristic properties of the substance:(size, shape, or state of matter)

13. Chemical Changes
A new substance is formed: it has different characteristic properties than the original substance
Chemical changes are NOT reversible
A chemical change has generally occurred if:
there is a color change
a gas is given off
a new substance is formed
heat or light is produced
a residue is formed

14. Phase change Dissolution Deformation Synthesis Decomposition Oxidation
Physical
Chemical
Phase change
Dissolution
Deformation
Synthesis
Decomposition
Oxidation
Precipitation

15. Physical or Chemical Change?
Painting Wood
PHYSICAL

16. Physical or Chemical Change?
Burning Paper
CHEMICAL

17. Physical or Chemical Change?
Digestion of food
CHEMICAL

18. Sugar dissolving in water PHYSICAL
Physical or Chemical Change?
Sugar dissolving in water
PHYSICAL

19. Iron turning red when heated PHYSICAL
Physical or Chemical Change?
Iron turning red when heated
PHYSICAL

20. Physical or Chemical Change?
Evaporation
PHYSICAL

21. A pond freezing in winter PHYSICAL
Physical or Chemical Change?
A pond freezing in winter
PHYSICAL

22. Physical or Chemical Change?
Melting ice
PHYSICAL

23. Physical or Chemical Change?
Cutting wire
PHYSICAL

24. Physical or Chemical Change?
Painting fingernails
PHYSICAL

25. Physical or Chemical Change?
Cutting fabric
PHYSICAL

26. Physical or Chemical Change?
Baking muffins
CHEMICAL

27. Physical or Chemical Change?
Shattering glass
PHYSICAL

28. Decomposition of old leaves CHEMICAL
Physical or Chemical Change?
Decomposition of old leaves
CHEMICAL

29. Physical or Chemical Change?
Wrinkling a shirt
PHYSICAL

30. Physical or Chemical Change?
An old nail rusting
CHEMICAL

31. Some Examples Physical Chemical Examples: water boiling
freezing cubes of ice
tearing paper
crushing a can
molding clay
butter melting on warm toast
Examples:
milk goes sour
jewelry tarnishes
a nail or screw forms rust
fried egg
your stomach digesting food
lighting a match

32. Compounds vs Mixtures Mixtures Compounds
Combine chemically forming molecules
Not chemically combined
Combine in set proportions
Can combine in any proportion
Separated chemically
Separated physically

33. Separation Techniques

34. Why would we want to separate mixtures?
to purify water so that it is safe to drink
to extract a mineral from rocks to be able to use (example, quartz or gold)
to eliminate the pulp in freshly squeezed juice
to make soup broth

35. What we have to think of when we separate mixtures…
We need to look for a difference between the parts of the mixture and then use a separation method that takes advantage of this difference.
These are some of the properties that can be used:
The size of the particles
The density of a substance
The boiling point of a substance
The solubility of a substance

36. Ways to Separate Mixtures
Sedimentation and decantation
AKA : settling out and pouring out
When it works:
The size of the particles of a substance have to be large enough to settle to the bottom of the container.
The larger the size of the particles the faster they will settle to the bottom of the container.
The liquid above the sedimented particles should be quite clear and can be poured off easily.
This method only works for heterogeneous mixtures!
When it doesn’t work:
As the size of the particles get smaller , it may take too long for them to settle to the bottom of the container and the particles may also be easily stirred up if we try to pour off the liquid above the particles .

37. Examples of S&D Examples:
noodles or vegetables in a soup settle to the bottom
muddy water (mud settles to the bottom)
orange juice that has pulp
salad dressing made of oil and vinegar

38. Ways to Separate Mixtures
2) Filtration
When it works:
The size of the particles of a substance have to be too large to pass through the holes of a filter .
This method only works for heterogeneous mixtures!
Downfall:
Filtration takes time and may take longer as the residue accumulates on the filter.
Vocabulary:
Residue: is what is left on the filter
Filtrate: is the liquid that passes though the filter

39. Filtration Mixture of solid and liquid Stirring rod Funnel
Filtrate (liquid
component
of the mixture)
Filter paper
traps solid
Funnel

40. Ways to Separate Mixtures
3) Distillation
When it works:
The substance in the mixture with the lowest boiling point will evaporate first and will then condense in another cooled container.
This method is the only one that works for SOLUTIONS! (homogeneous mixture)
When it Doesn’t work
-This method cannot be used if 2 substances have the same boiling point
Vocabulary
Distillate: is the liquid that evaporates
Residue: is the substance left behind in the original container

41. Examples of Distillation
separating salt from saltwater
making distilled water in the lab
commercially distilling alcohol (ethanol used for thermometers)

42. .
DIstillation
Separates homogeneous mixture on the basis of differences in boiling point