1. Physical & Chemical Changes
Changing Matter
Physical & Chemical Changes

2. Lesson Goals and Objectives
I can
Explain what physical changes are and how matter can change from one state to another.
Explain how chemical changes can cause some kinds of matter to become new matter.
distinguish between a physical and chemical change.

3. Matter is anything with volume and mass.
Reviewing Matter
Matter is everywhere.
Matter is anything with volume and mass.
How we identify matter: Properties
Matter has properties
Two basic types of properties that we can associate with matter.
Physical properties
Chemical properties

4. electrical conductivity ductility color malleability
Physical Properties
Anything that can be observed without changing the identity of the substance. (Tends to be measurable.)
melting point
density
boiling point
thermal conductivity
electrical conductivity
ductility
color
malleability

5. Reactivity to other chemicals
Chemical Properties
The way a substance may change or react to form new substances
heat of combustion
Oxidation
reactivity with water
Flammability pH
Reactivity to other chemicals
Chemical properties of matter describes its "potential" to undergo some chemical change or reaction by virtue of its composition. What elements, electrons, and bonding are present to give the potential for chemical change.
It is quite difficult to define a chemical property without using the word "change". Eventually you should be able to look at the formula of a compound and state some chemical property. At this time this is very difficult to do and you are not expected to be able to do it.
For example hydrogen has the potential to ignite and explode given the right conditions. This is a chemical property.
Metals in general have they chemical property of reacting with an acid. Zinc reacts with hydrochloric acid to produce hydrogen gas. This is a chemical property.

6. Matter is constantly experiencing both chemical and physical changes.
Changing matter
Matter is constantly experiencing both chemical and physical changes.
Matter can be changed two ways
Physically
Chemically

7. Physical Changes
A Physical change is a change in a substance that does not change the identity of the substance.
no new substances are formed.
Change in the form of a substance, not in its chemical composition.
Substance may seem different, but the way the atoms link up is the same.
A physical change alters the form of a substance, but does not change it to another substance.
Physical changes are those changes that do not result in the production of a new substance.  If you melt a block of ice, you still have H2O at the end of the change. 

8. Physical Change – examples
Change in size or shape
Mass
Volume
Density
weight
Making a mixture
2 or more types of matter (substances) mixed together
Not in specific amounts
Can be separated physically
Dilutions
Dissolving

9. Physical Change – examples
Change in phase
Melting (solid to liquid)
Boiling (liquid to gas)
vaporation (liquid to gas)
Condensation (gas to liquid)
Freezing (liquid to solid)
Sublimation (solid to gas)
Deposition (gas to solid)
In all three phases, water molecules are still intact.
Motions of molecules and the distances between them change.

10. Physical Change Physical changes might be caused by: Grinding Cutting
Crushing
Bending
Breaking
Heating/cooling (change in phase)
squishing

11. Physical Change
Evidence that a physical change has occurred might include:
Change in shape
Change in form
Change in size
Change in phase (This is always a physical change!)
Physical changes are usually reversible

12. If you remember, ice is water in the solid state.
When you drop the ice cube into the liquid, it begins to melt because the temperature is higher than that of the ice cube.
It's like putting a snowman on your front lawn in July.
The ice cube becomes liquid water.
This is an example of a physical change.
The solid water turned to liquid water.

13. Physical Change

14. Special types of physical changes where any object changes state, such as when water freezes or evaporates, are sometimes called change of state operations.

15. More Examples of Physical Changes
Change in size, shape, or color
Pencil shavings
Torn Paper
Crushed ice
Sugar dissolved in water
Painting a wall

16. Can you think of ways that you can physically change a sheet of paper?
Cutting
Tearing
Shredding
Folding
Painting
Writing on
Gluing

17. Physical change
What could you do to these items to cause a physical change to occur?

18. Physical and Chemical Changes
How to tell the difference

19. If you break a bottle, you still have glass
If you break a bottle, you still have glass.  Painting your nails will not stop them from being fingernails.  Some common examples of physical changes are: melting, freezing, condensing, breaking, crushing, cutting, and bending.

20. Some, but not all physical changes can be reversed
Some, but not all physical changes can be reversed. You could refreeze the water into ice, but you cannot put your hair back together if you don’t like your haircut!

21. Which of the following are physical properties?
Concept check
Which of the following are physical properties?
liquid at room temperature
reacts with metals to form H2 gas
acids and bases combine to form water and a ‘salt’
boils at 145 degrees Celsius

22. CHEMICAL PROPERTIES
Remember?
Chemical properties can ONLY be observed AS the substances are changing into different substances.

23. Chemical Changes Chemical changes do alter the identity of a substance
In other words, a chemical change is when something changes into an entirely different substance
The composition of the substance changes.
The substances present at the beginning of the change are not present at the end
new substances are formed.
The change cannot be “undone.”

24. Chemical change
Chemical changes occur when a chemical reaction causes bonds between atoms to break or to form.

25. Atoms are re-arranged, NOT created or destroyed
Chemical Changes
Atoms are re-arranged, NOT created or destroyed

26. Examples of chemical changes
When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon.  When you light your Bunsen burner in lab, you are carrying out a chemical reaction that produces water and carbon dioxide. 

27. Reactivity How readily (easily) a substance combines chemically with other substances.
Reactions between Substances
Reactions with Acid
Reactions with Oxygen
Reactions with Electricity
Vinegar + baking soda = release of Carbon Dioxide Gas
OXIDATION
Iron + Oxygen = rust
Silver Plating
Sodium + chloride = salt
Silver + sulfur in the air = tarnish

28. WHAT’S THE POINT OF THIS?
Reacts with acids
There were a few horror movies made in the 70s, 80s, and 90s and even this decade starring these guys:
Besides many gross events, one of the things the people in the movie quickly realize is that if you cut or damage one of these aliens, it bled a concentrated acid that would “melt” or “corrode” anything it came into contact with. Nasty.
WHAT’S THE POINT OF THIS?

29. DEBUNKING THE MYTH
Well, I think those movies have perpetuated a myth common to many people that acids are all super-harmful, extremely dangerous, eat-through-anything chemicals. Really? Here’s some examples of acidic compounds:
So…not ALL acids are instant-death, huh.
Now, some of those acids can be pretty powerful substances. The next time you lose a tooth or eat a chicken wing, soak that bone in coke for a few days and observe it…no wonder dentists don’t like soda. Acids (and their opposites…bases) are just reactive chemicals that behave in certain ways. Here are some common bases:

30. Is There a Point To This?
Well, yeah. Acids and bases are just a few of MANY kinds of chemicals that can react with each other. When chemicals react, they rearrange their atoms & molecules to produce new substances. New substances! Chemical change!
You’re familiar with baking soda and vinegar, right?
And we
all know
that gas
under
high
pressure
can be
fun…or
deadly.
They combine…
They react and make a
new substance (CO2 gas)

31. FLAMMABILITY: A material’s ability to BURN in the presence of OXYGEN

32. Other Examples Wood burning Metal rusting Food digesting
Gasoline burning
Cake baking
Respiration
Photosynthesis
Decomposition
Polymerization

33. Electrolysis of Water
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34. Electrolysis of Water Water decomposes to hydrogen and oxygen gases.
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36. Common Errors
Ice melting, water freezing, water evaporating, and steam condensing are all examples of a state change.
These are physical changes, not chemical.
Diluting a solution is a physical change, even if the color becomes more faint.

37. Concept Check Pulverizing (crushing) rock salt Burning of wood
How many of the following are examples of a chemical change?
Pulverizing (crushing) rock salt
Burning of wood
Dissolving of sugar in water
Melting a popsicle on a warm summer day
1 (burning of wood)

38. Concept Check Sugar fermenting to form ethyl alcohol
Classify each of the following as a physical or chemical change.
Sugar fermenting to form ethyl alcohol
Iron metal melting
Iron combining with oxygen to form rust
chemical
physical
Sugar fermenting to form ethyl alcohol.
Chemical change: describes how sugar forms a new substance (ethyl alcohol) via a chemical reaction.
Iron metal melting.
Physical change: describes a state change, but the material is still iron.
Iron combining with oxygen to form rust.
Chemical change: describes how iron and oxygen react to make a new substance, rust.
Copyright © Cengage Learning. All rights reserved

39. How do we know if a chemical change has occurred?
Possible Indicators of a Chemical Change
Energy Release
(a change in temperature heats up or cools down/light)
ex: match burns, cold packs cool
Forms bubbles or gas
ex: vinegar + baking soda  CO2
Permanent unexpected color change
ex: burning wood changes its color
odor released
new gases
ex: baking bread creates
Irreversibility
difficult to reverse
ex: can’t turn a cookie back into dough
Production of a gas
ex: vinegar and baking soda produces CO2
Formation of a precipitate
ex: vinegar and milk forms curds (cheese)
Change in temperature
ex: water and baking soda feels cool
ex: hydrogen peroxide and yeast feels hot
Change in color
ex: pH indicator going from colorless to color
NOT an ex: food coloring in water
Light is produced and/or sound is given off
Ex: fireworks

40. Chemical Change indicators
Evidence of a chemical reaction
Difficult or impossible to reverse
Formation of gas
Formation of precipitate
Change in color
Change in energy
Endothermic Absorbs heat energy (gets cold)
Exothermic Releases heat energy (gets hot)
Alka-Seltzer: (Baking soda or sodium bicarbonate) NaHCO3 + Citric acid ---> CO2 + H2O + Sodium Citrate

41. Evidence of Chemical Change

42. Energy Release
A chemical reaction often releases forms of energy such as light and
heat.
Glow sticks work when a capsule of
phenyl oxalate is broken (by you) and it mixes
with hydrogen peroxide. This releases
energy that causes a colored dye to glow with
light.
When you burn something, the fuel is
reacting with oxygen in the air to produce
fire–a combination of heat AND light.

43. Forms bubbles or gas
Well, back to vinegar and baking soda…the huge release of gas is
a good sign that a new substance (the gas, duh) has been produced.
Hydrochloric acid creates hydrogen gas
when reacting with zinc metal.

44. color
A permanent, unexpected change in color often lets you know that a
substance has been chemically, not physically, changed into a new
substance.
mmm…the perfect cookies
Whoa!  The total change in color
to “char black” is a chemical change.

45. Perfectly good cookies.
odors
Yes. Here’s another one…imagine what this:
…smells like. Probably not the
way it smelled 10 minutes before
being pulled out of the oven.
odor released
ex: baking bread creates
new gases
Perfectly good cookies.
RUINED.

46. They let you know that a chemical change has happened?
One Last One…
What do the previous four indicators of chemical change have in
common?
They let you know that a chemical change has happened?
Well, yeah, no kidding.
BESIDES that?

47. All Hard to Reverse!
Yeah! Imagine trying to stuff the heat and light back into a burning
candle.
Uh huh…ouch.
Or imagine trying to get burned cookies to go back to
being brown. Or take it another step. Try to get a
nicely baked cookie to “unbake” and turn into cookie
dough.
gee…how?

48. Irreversibility difficult to reverse
ex: can’t turn a cookie back into dough

49. Chemical Changes

50. The OTHER kind of change
So…the other kind of changes tend to:
Not release heat or light
Not release gas or bubbles
Not change the color of something permanently
Not release new odors
Be somewhat reversible
You can cut, mash, smash, stretch, flatten, divide, shave, freeze, thaw
cookie dough and it’s STILL cookie dough. Those kinds of changes
haven’t made new substances.
physical
Let’s see you put this all together. A ____ change happens when no new substance is made. The opposite kind of change, a ____ change, DOES create a new substance.
chemical

51. Practice, practice, practice
I can distinguish between a physical and chemical change.

52. What kind of change is it if someone...
Tears up paper?
Physical change
Mixes salt and water?

53. What kind of change is it if someone...
Burns paper?
Chemical change
Evaporates salt water?
Physical change

54. What kind of change is it if someone...
Mixes vinegar and baking soda?
Chemical change

55. Quiz time! Which life cycle is most similar to a chemical change? Why?
Grasshopper = Eggnymphadult
Butterfly = egglarvapupaadult

56. What type of change is most likely occurring here?
Quiz time!
What type of change is most likely occurring here?
How do you know?

57. What type of change is most likely occurring here?
Quiz time!
What type of change is most likely occurring here?
How do you know?

58. What type of change is most likely occurring here?
Quiz time
What type of change is most likely occurring here?
How do you know?

59. Physical or Chemical Change?
Water evaporates from the ocean.

60. Physical or Chemical Change?
The yolk of an egg, which contains sulfur, causes tarnish to form on silver.

61. Physical or Chemical Change?
The ice on a lake melts to become water in the lake.

62. Physical or Chemical Change?
Charcoal in a fire turns to ash after several hours.

63. Physical or Chemical Change?
A pencil is sharpened in a pencil sharpener, leaving behind shavings.

64. Physical or Chemical Change?
A battery makes electricity to turn on a flashlight.

65. Physical or Chemical Change?
A bicycle rusts when left in the rain.

66. Physical or Chemical Change?
A shirt is accidentally torn in the washing machine.

67. Physical or Chemical Change?
A log is split in two by an axe.

68. Chemical or Physical Change?
Cutting paper?
Physical

69. Chemical or Physical Change?
Ice melting?
Physical

70. Chemical or Physical Change?
Bread toasting?
Chemical

71. Chemical or Physical Change?
Rocket fuel burning?
Chemical

72. Chemical or Physical Change?
Sawing wood?
Physical

73. Chemical or Physical Change?
Metal rusting?
Chemical

74. Chemical or Physical Change?
Disappearing puddle?
Physical

75. Chemical or Physical Change?
Candle burning?
Chemical

76. Chemical or Physical Change?
Dry ice?
Physical

77. Physical or Chemical Change?
Painting Wood
PHYSICAL

78. Physical or Chemical Change?
Burning Paper
CHEMICAL

79. Physical or Chemical Change?
Digestion of food
CHEMICAL

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

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

82. Physical or Chemical Change?
Evaporation
PHYSICAL

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

84. Physical or Chemical Change?
Melting ice
PHYSICAL

85. Physical or Chemical Change?
Cutting wire
PHYSICAL

86. Physical or Chemical Change?
Painting fingernails
PHYSICAL

87. Physical or Chemical Change?
Cutting fabric
PHYSICAL

88. Physical or Chemical Change?
Baking muffins
CHEMICAL

89. Physical or Chemical Change?
Shattering glass
PHYSICAL

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

91. Physical or Chemical Change?
Wrinkling a shirt
PHYSICAL

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

93. Concept check
Substance A is a yellow liquid and substance B is a blue liquid. The two are mixed and form a green liquid and a white solid.
What evidence suggests a chemical change occurred?
What other things could you look for to determine if there was a chemical change?

94. sToP & tHinK - which shows physical change and which shows chemical change?
link to change animation #1
link to change animation #2

95. Physical and Chemical Changes
Quiz
Number your paper (1-10)

96. 1. A. Physical Change B. Chemical Change
Rusting nails

97. 2. A. Physical Change B. Chemical Change
Effervescent tablet

98. 3. A. Physical Change B. Chemical Change
Cut paper

99. 4. A. Physical Change B. Chemical Change
Vinegar and Baking soda

100. 5. A. Physical Change B. Chemical Change
Salt and water

101. 6. A. Physical Change B. Chemical Change
Broken glass

102. 7. A. Physical Change B. Chemical Change
Burning wood

103. 8. A. Physical Change B. Chemical Change
Ice melting

104. 9. A. Physical Change B. Chemical Change
Removing iron filings from a mixture

105. 10. A. Physical Change
B. Chemical Change
Boiling water

106. Check your paper and place in notebook
1. B - Chemical
2. B - Chemical
3. A - Physical
4. B - Chemical
5. A - Physical
6. A - Physical
7. B - Chemical
8. A - Physical
9. A - Physical
10. A - Physical