1. Alkanes( 烷 ) petroleum and natural gas contain lots of hydrocarbon( 碳氫 化合物 / 烴 ) general formula : C n H 2n+2 Physical properties of alkanes The viscosity of liquid alkanes increases with a greater number of atoms. Alkanes are insoluble in water but soluble in many organic solvent.

2. Physical properties of alkanes( 烷的物理性質 ) There is a general trend in melting point; boiling point; density(no. of C  and the properties  also); Why ? The molecular size increases, so the van der Waals’ forces become greater.

3. Use of alkanes Butane( 丁烷 ) (liquefied 液化 ) C 18-20 alkane

4. Paraffin oil(mixture of alkanes) Which can preventing oxygen contact sodium metal directly.

5. Chemistry properties of alkanes Higher members of homologue series of alkanes usually react more slowly than lower members. Alkanes are saturated hydrocarbon. They are quite unreactive. Do not react with acids, alkalis, dehydrating agents, oxidizing agents and reducing agents. 1. Combustion( 燃燒 ): the products for completely combustion are carbon dioxide and water.  H < 0 C x H y + (x + y/4) O 2  x CO 2 + y/2 H 2 O

6. Liquefied petroleum gas(LPG) Blue flame Candle sooty yellow flame

7. 2. Decomposition by heat: cracking( 裂解 ) Large molecules of alkanes  small molecules of alkanes + smaller molecules of alkenes Products of cracking can be used as : alkanes :fuel alkenes raw material of making polymers