1. Taking Compounds Apart
Chemistry

2. Learning Goals To be able to explain how compounds come apart
To be able to identify gases

3. Elements cannot be broken down into simpler substances
Compounds can be broken down because they are made of two or more elements

4. Decomposition
Refers to a chemical change in which compounds are broken down into simpler substances
In general, compounds do not break down by themselves
They require energy obtained in one of two ways:
Using electricity
Adding thermal energy (heat) to the compound

5. Using Electricity
Electrolysis – process during which electricity is used to break down a compound into simpler substances
Electrolysis of Water – when electricity is passed through water, some of the water molecules (H2O) break down to form hydrogen gas and oxygen gas

6. Adding Thermal Energy Decomposition occurs when a match is lit
The friction between the match head and the rough strip on the matchbox releases thermal energy
This causes chemicals on the match head to break down and catch fire

7. Baking soda is added to dough and cake batter because heat from the oven causes the baking soda to break down into other chemicals, including carbon dioxide (CO2) bubbles, which cause the bread and cake to rise
A catalyst is a substance that speeds up a chemical change without being consumed or chemically changed itself

8. Gas Tests

9. Hydrogen gas can be detected using a flaming splint test – a flaming splint will ignite the gas and make a “pop” sound if hydrogen is present
Oxygen gas can be detected using a glowing splint test – a glowing splint will reignite if oxygen is present
Carbon dioxide gas can be detected using a flaming splint test – a flaming splint will be extinguished if carbon dioxide is present

10. Success Criteria I CAN explain decomposition
I CAN identify the gas present based on a test

11. To Do… Late work (Element poster, Bohr diagrams) Worksheet
Prepare for Quiz (tomorrow)