1. Chemical Reactions and Physical Changes
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2. Physical Change…
To understand chemical reactions, we must first take a look at what exactly a PHYSICAL Change is…
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3. Physical Change…
Physical Change – the atoms or molecules in a sample of matter are moved around or might experience a phase change, but do not turn into a new substance with new chemical properties
Examples:
Boiling water
cutting up a cookie
melting a piece of ice
dissolving sugar into water
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4. Mixtures can be separated by physical changes
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5. DISTILLATION
Distillation is a method of separating homogenous mixtures based on differences in their boiling points
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6. Filtration
Filtration = the mechanical or physical separation of solids from fluids (liquids or gases) by interposing a medium through which only the fluid can pass.
Used to separate heterogeneous mixtures
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7. Physical Properties
Are properties that can be measured during a physical change
Physical properties include:
Boiling point
Density
Hardness
Texture
Melting point
Color
Viscosity
odor
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8. Chemical Reactions
In a chemical reaction bonds are broken and new bonds are formed
the atoms and molecules are rearranged and turned into new substances with new properties
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9. Chemical Reactions Examples:
Burning a log
Cooking an egg
Digesting a Twinkie
A nail rusting over time
Some clues to let you know you have a chemical reaction…
Energy is released or absorbed (fire, Heat)
A smell is produced
A color change occurs
A gas is emitted
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10. Chemical Properties
Chemical properties are observed when a chemical reaction occurs
Examples:
Sodium is highly reactive with water
Iron will rust in the presence of oxygen
pH of an acid
Temperature at which
magnesium will burn
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11. Chemical Reactions

12. Law of Conservation of Matter
When a chemical reaction occurs, matter is not created and it is not destroyed
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13. How many carbon atoms did we end up with? How many oxygen atoms?
In the chemical reaction below, how many carbon atoms did we start with? How many oxygen atoms?
How many carbon atoms did we end up with? How many oxygen atoms?
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