lesson: mixtures & compounds. science differentiation in action a mixture is made of two or more...
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Lesson: Mixtures & Compounds
Science Differentiation in action
A mixture is made of two or more substances mingled together but not chemically combined.
Air is a mixture
Sea water is a mixture
Science Differentiation in action
Air contains:
nitrogen
oxygen
carbon dioxide
Science Differentiation in action
Sea-water contains:
water
salt
The Dead Sea has a high concentration of salt.
Science Differentiation in action
A compound is formed when two or more elements combine chemically.
Carbon dioxide gas is a compound formed when one atom of carbon is combined chemically with two atoms of oxygen (CO2).
oxygen
carbon
Science Differentiation in action
A compound is formed when two or more elements combine chemically
Water is a compound formed when one atom of oxygen is combined chemically with two atoms of hydrogen (H2O).
hydrogen
oxygen
Science Differentiation in action
Examples of compounds
Water (H2O)
Carbon dioxide (CO2)
Magnesium oxide (MgO)
Iron sulfide (FeS)
How many atoms are in each molecule of the above compounds?
Science Differentiation in action
Differences between mixtures and compounds
MIXTURES
• Made of 2 or more substances
COMPOUNDS
• Is a single substance
• Proportion of each substance may vary
• Proportion of each element is fixed
• Properties are the same as the properties of the substances mixed together
• Properties are different to the elements involved
• Generally easy to separate • Difficult to separate
Science Differentiation in action
A compound is a completely new substance with its own properties.
Water (H2O) is a liquid that can put out fires.
Yet, the elements that make it are very different.
Hydrogen (H2) is an explosive gas.
Oxygen (O2) is needed for burning.
hydrogen
oxygen
Science Differentiation in action
Carbon dioxide (CO2) is a colourless gas used to put out fires.
Carbon (C) is a black solid.
Oxygen (O2) is needed for burning.
oxygen
carbon
A compound is a completely new substance with its own properties.
Science Differentiation in action
Magnesium oxide (MgO) is a dull white solid.
Magnesium (Mg) is a soft shiny metal.
Oxygen (O2) is needed for burning.
A compound is a completely new substance with its own properties.
Science Differentiation in action
Iron sulfide (FeS) is a grey solidthat is not attracted to magnets.
Iron (Fe) is a metalthat is attracted to magnets.
Sulfur (S) is a bright yellow solid.
A compound is a completely new substance with its own properties.
Science Differentiation in action
1. Is air a mixture or a compound?
Review Questions
2. What elements is carbon dioxide made from?
3. Name one difference between a compound and a mixture.
4. Hydrogen is explosive and oxygen is needed for burning. What compound can both of these elements make?
Science Differentiation in action
How could you check if a substance was an element or a compound?
Question to think about!
hydrogen
oxygen