Presentation is loading. Please wait.

Presentation is loading. Please wait.

TOPIC 5 Hydrocarbons Hydrocarbons are substances that contain Hydrogen and Carbon only. Hydrocarbons are divided into a series of families or groups.

Similar presentations


Presentation on theme: "TOPIC 5 Hydrocarbons Hydrocarbons are substances that contain Hydrogen and Carbon only. Hydrocarbons are divided into a series of families or groups."— Presentation transcript:

1

2 TOPIC 5 Hydrocarbons

3 Hydrocarbons are substances that contain Hydrogen and Carbon only. Hydrocarbons are divided into a series of families or groups called Homologous Series. A Homologous Series is a group of compound which have a General Formula and are chemically similar. Examples of Homologous Series are the: Alkanes, Alkenes and Cycloalkanes. Hydrocarbons

4 The Alkanes have a general formula of CnH2n+2 They run from C1 –C60 approx. C1-C4 are gases C5-C17 are liquids C17-C60 are Waxy Solids As we progress between successive members of the series we find that there is a difference of CH2 in their formulae. As a direct result there is a regular increase in their Boiling Points since more energy is required to break up the longer chains. All Alkanes are flammable, have a pH of 7 and are insoluble in water. The Alkanes

5 The Alkane members Name Molecular Formula Common Uses Methane CH 4 Nat.Gas.Household heating & cooking Ethane C2H4C2H4C2H4C2H4 Propane C3H6C3H6C3H6C3H6 Portable cooking and Heating gas Butane C 4 H 10 Lighter fuel/Calor Gas Pentane C 5 H 12 Hexane C 6 H 14 Octane * C 8 H 18 Petrol derivative Diesel *C 17 H 36 Transport Bitumen *>C 60 Road/Playgrounds

6 The Alkenes are another Homologues Series with General Formula CnH2n All Alkenes must have a C=C double bond. As a result the first member of the series is Ethene ie. Methene does not exist. Ethene C2H4C2H4C2H4C2H4 Propene C3H4C3H4C3H4C3H4 Butene C4H8C4H8C4H8C4H8 Pentene C 5 H 10 Hexene C 6 H 12 Only the first three are gases Ethene & propene are important starting materials in making other chemicals The Alkenes

7 The Cycloalkanes are another Homologous series with General Formula C n H 2n The Cycloalkanes are another Homologous series with General Formula C n H 2n The Cycloalkanes are Ring compounds which means that the first member of the series is cyclopropane. The Cycloalkanes are Ring compounds which means that the first member of the series is cyclopropane. It should be noted that the Cycloalkanes have the same general formula as the alkenes i.e. C n H 2n but that the Cyloalkanes are Saturated whereas the Alkenes are Unsaturated It should be noted that the Cycloalkanes have the same general formula as the alkenes i.e. C n H 2n but that the Cyloalkanes are Saturated whereas the Alkenes are Unsaturated The Cycloalkanes

8 Isomers are molecules with the same Molecular formula but different structural formula. Note: There must be the same number of carbon and hydrogen atoms but there also must be a completely different arrangement of Carbon atoms. Isomers

9 Crude Oil is a mixture of Hydrocarbons called Fractions To Separate the oil into its component fractions we first boil it. This process is called Fractional Distillation. A After Fractional Distillation there are a large number of Long-Chain Hydrocarbons left. To meet market demand these long-chain Hydrocarbons are broken up into smaller more desirable Hydrocarbon Chains ie they are said to be Cracked Cracking of Crude Oil

10 Steel Wool acts as a Catalyst The hot Paraffin vapour is passed over the heated steel wool The gas collected is tested with Bromine water Alkane When an Alkane is cracked one of the products is always Unsaturated C 16 H 34 C 13 H 28 + C 3 H 6 Safety : Beware of Suck-back Cracking of Crude Oil

11 An Unsaturated compound is one that contains a C=C double bond. A Saturated compound is one that contains C-C single bonds only. Alkanes are Saturated and Alkenes Unsaturated. The Test: Add Br2(aq) to both an alkane and alkene. Alkenes quickly decolourise the Br2(from brown to clear) whereas alkanes only slowly decolourise the Br2 in the presence of UV light. Alkene and Bromine water shaken together Alkane and Bromine water shaken together The Test for Saturation/Unsaturation


Download ppt "TOPIC 5 Hydrocarbons Hydrocarbons are substances that contain Hydrogen and Carbon only. Hydrocarbons are divided into a series of families or groups."

Similar presentations


Ads by Google