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Mixtures and Pure Substances
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Uploaded: 6 years ago
Category: General Science
Type: Lecture Notes
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Filename: 3c Mixtures and Pure Substances.pptx
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Transcript
Mixtures and Pure Substances
All matter is either a pure substance or a mixture
Physical and chemical properties show us whether a substance is “pure” or a mixture
Pure Substances
Made of only ONE kind of matter
Has a unique set of properties
May be either an element or a compound
Element
Material that cannot be broken down into any simpler substance
Are the basic building blocks for all compounds
Hydrogen (H) ; Carbon (C) ;
Oxygen (O)
Compound
Combination of two or more elements in a fixed proportion
When elements combine in specific proportions, they form a compound
Water (H2O) ; Carbon Dioxide (CO2)
Mixtures
Combination of pure substances
However: substances in a mixture do not combine chemically as happens when a compound is formed
There are 4 main types of mixtures
Mechanical mixtures
Different substances that make up the mixture are visible
Also called heterogeneous mixture
Example: soil; package of mixed vegetables
Solution
Different substances that make it up are not separately visible
One substance is dissolved in another
Example: sugar in coffee; gas dissolved in liquid (Carbonated pop)
Did you Know?
Chemist call a substance dissolved in water an aqueous solution
Suspension
Is a cloudy mixture in which tiny particles of one substance are held within another
Can be separated when poured through a filter
Example: Tomato juice
Colloid
Also a cloudy mixture
The particles of the suspended substance are so small that they cannot be easily separated out from the other substance
Example: Milk; Ketchup
Matter
Pure Substance
Mixtures
Elements
Compounds
Solutions
Mechanical Mixtures
Colloid
Suspension
Observing Change in Matter
Matter can undergo two types of change
Physical Change
One in which a material changes from one state to another
Material can also physically change back into its original state
Chemical Change
Occurs when two or more materials react and create new materials
New materials have completely different properties
Evidence of Chemical Change
Change in Colour
Change in Odour
Formation of a solid or gas
Release or absorption of energy
Freeze Drying Food
Food is Frozen-water turns into ice
Frozen food up in a pressure- pressure reduced until solid turns to gas
Leaves food 10% original mass & does not have to be refrigerated
Meal, Ready to Eat
Uses freeze dried food in a special package called a “Flameless Ration Heater”
Good for Soldiers, astronauts, mountain climbers
Corn based Products used by Humans
Chemical made from corn can be used to make soda pop bottles, remove paint, nail polish, fuel for cars
Products are not as harmful to the environment, renewable form of fuel
Difference between Chemical and Physical Change
Physical Change is a change in state, can be reversed
Chemical Change there is a change in properties, new substance formed.
Event
Changes in Matter
Observable Change
Type of Change
Baking Bread
Burning Wood
Freezing Water
Mixing sugar and Water
Evidence of Chemical change
-Change in Colour
-Change in Odour
-Formation of a solid or gas
-Release or absorption of heat energy
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