1. Write a balanced symbol equation to show methane burning in oxygen
CH4+ 2 O2  CO2 + 2 H2O
methane + oxygen  carbon dioxide + water

2. Chemistry for a sustainable world – C7 The alkanes
Learning Objectives:
To be able to write a balanced equation for the combustion of a hydrocarbon.
To know what alkanes and alcohols are.
Key words: hydrocarbon, combustion, alkane, alcohol

3. What are all these?
Paraffin wax
Butane gas
Candle wax

4. Activity – More about alkanes
Complete activity 1+2 on Ac7.1. For each model write down the molecular formula.
What is the relationship between number of carbon atoms and number of hydrogen atoms in each alkane?
Try to write down a general formula to show the number of carbon and hydrogen atoms in an alkane.
Use the table in activity 3 on Ac7.1 to describe in words how the boiling point of an alkane varies with chain length.
Watch the demonstrations and make observations as shown in activity 4 on Ac7.1.
Now explain why alkanes are so unreactive.

5. Alkanes – Summary
Alkanes
CnH2n+2
(n = 1, 2, 3 etc)
Alkanes are SATURATED molecules because they contain ONLY single bonds (every carbon is attached to 4 different atoms).
Alkanes are generally very unreactive.
Alkanes do not mix with water.
Alkanes burn with a smokey flame.
Alkanes are used as fuels and can be solid (candle wax), liquid (hexane) or gas (propane gas, butane gas)

6. Changing the reactivity by changing the atoms….
R is an alkane chain
Look at the models of methanol and ethanol to see how they are different
NOT industrial alcohol as used in the lab!!

7. Alcohol family summary
OH is a functional group.
Functional groups give compounds their different chemical and physical properties.
In this case, the OH group makes alcohols more reactive than alkanes. E.g. They burn with a blue flame.
OH here is not OH- ion because it is COVALENTLY bonded not IONIC here!!