1. Hydrocarbons Compounds containing hydrogen and carbon only
We get them from crude oil
They are made up of molecules
A molecule is made up of 2 or more atoms joined by covalent bonds.
Hydrogen is in group 1 and has 1 outer electron
Hydrogen can form one bond
Carbon is in group 4 and has 4 outer electrons
Carbon can form 4 bonds

2. ALKANES H C Methane CH4 Structural Formula Molecular Formula Name C C
A family of hydrocarbons H C
Methane
CH4
Structural
Formula
Molecular
Formula
Name
C C H
C2H6
Ethane

3. ALKANES
C C H C
Propane
C3H8 H
C C
C4H10
Butane

4. ALKANES
Pentane
C5H12 H
C C C

5. Hexane – How many hydrogens?C6 H H C H

6. Each carbon in the chain has a hydrogen above and below so multiply 6 by two = 12
There is also a hydrogen at each end. Add 2.
Total number of hydrogens = (2x6) + 2 =
=14 C H

7. Give the complete formula for each of these hydrocarbons
Give the complete formula for each of these hydrocarbons. You are given the number of carbons. C8
C10
C15
C31
C100 Cn
H18 (2 x 8) + 2 = =18
H22 (2 x 10) + 2 = = 22
H32 (2 x 15) + 2 = = 32
H64 (2 x 31) + 2 = = 64
H202 (2 x 100) + 2 = = 202
H2n + 2 (2 x n) + 2

8. Hydrogen and carbon only
Hydrocarbons
Hydrogen and carbon only
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
Pentane C5H12
Hexane C6H14
Heptane C7H16
Octane C8H18
Nonane C9H20
Decane C10H22 My
Elephant
Prefers
Buns
Pity He
Has
Only
Nice
Doughnuts
Alkanes
General formula
CnH2n+2

9. H CH3CH3 C C H CH3CH2CH3 C C C Shortened structural formula

10. Isomers H C C H C C C Both butane Both C4H10 Same molecular formula
Different structural formula

11. In your jotter:
Draw the 3 isomers of pentane
At least 3 isomers of hexane

12. CYCLOALKANES
Cycloalkanes are ring compounds
The first cycloalkane is: H
C C C
Cyclopropane
C3H6

13. The second cycloalkane is:
Cyclobutane
C4H8

14. The third cycloalkane is:
Cyclopentane
C5H10

15. The fourth cycloalkane is:
Cyclohexane
C6H12

16. General formula CnH Cycloalkane Molecular Formula
Cyclopropane C3H6 2 x 3 = 6
Cyclobutane C4H8 2 x 4 = 8
Cyclopentane C5H x 5 = 10
Cyclohexane C6H x 6 = 12
Cycloheptane C7H x 7 = 14
Cyclooctane C8H x 8 = 16
General formula
CnH 2n

17. ALKENES C C H Ethene C2H4 Double bond
Alkenes are hydrocarbons which have a double bond
Double bond
C C H
Ethene
C2H4

18. H
C C C
Propene
C3H6 H
C C C
Butene
C4H8

19. General formula CnH Alkene Molecular Formula Ethene C2H4 2 x 2 = 4
Propene C3H6 2 x 3 = 6
Butene C4H8 2 x 4 = 8
Pentene C5H10 2 x 5 = 10
Hexene C6H12 2 x 6 = 12
General formula
CnH 2n

20. Write the molecular formula of:
a) the alkane with 6 carbons b) the alkane with 24 hydrogens
c) the cycloalkane with 20 carbons
d) the alkene with 100 hydrogens
Draw the structural formula of:
a) the alkene with 5 carbons b) the cycloalkane with 7 carbons
Give the general formula of
a) the alkanes b) the alkenes c) the cycloalkanes
Copy and complete:
a) Isomers have the same ____ formula but different ___ formula
Draw 2 isomers of heptane and 2 isomers of butene and 2 isomers of cyclopropane
What is meant by a hydrocarbon?
What is meant by a molecule?
What is produced when a hydrocarbon burns?
Which would have higher boiling point propane or pentane?
Which would be more flammable octene or butene?
Which would be more viscous cyclopropane or cyclooctane?

21. E A H H C C C C Single bond Double bond Hydrocarbons Alkanes Alkenes
Ethane
Ethene

22. The Bromine Water Test
Place a small amount of each hydrocarbon in a test tube. To each add a little bromine water. Bromine water is a brownish colour and when dilute is yellowish.
Set out your results by drawing up a table as shown below
Hydrocarbon Formula Result of test
Hexane C6H14
Hexene C6H12
Heptane C7H16
Octane C8H18
Cyclohexane C6H12

23. Br Br Br2 Test for ALKENES C C H H C C H H H ETHENE Bromine water
Decolourised

24. 1 Write out full structural formulae to show the reaction between:
Propene and bromine water
Butene and bromine water
Complete the following equations by putting in the missing compounds (first one is done for you).
C5H10 (pentene) + Br2  C5H10 Br2
C6H12 (hexene) + Br2  C6H12 Br2
_____ (_______) + Br2  C8H16 Br2
C4H8 (butene) + Cl2  _________
C5H10 (pentene) + ____  C5H12

25. ALKANE
C C H
ethane
Single bonds only
Saturated

26. ALKENE
C C H
ethene
Unsaturated
Has a C=C double bond.

28. Heat
Hydrocarbon
oil (C12H26)
Cracking
Aluminium oxide
catalyst
Product gas
water
Do not remove heat before taking the tube out of the water!
The gas produced decolourised bromine water – it contained an alkene.
The large liquid molecules have been broken (cracked) into smaller gas molecules.
Thermal cracking produces more useful small molecules from less useful large molecules.

29. 1 C12H26  C10H22 + ______ ( )
2 C18H38  C12H26 + ______ ( )
3 C20H42  C10H20 + ______ ( )
4 C30H62  C10H22 + C11H22 + ______ ( )
5 C19H40  C12H24 + C6H12 + ______ ( )
6 ______ ( )  C4H8 + C4H10

30. H H C H C H C

31. H C H
C C H H