Alkanes

Alkanes are saturated hydrocarbons, meaning they have only single bonds between adjacent carbon atoms. Alkanes with 1 to 4 carbon atoms in their molecules are gases at room temperature, those with 5 to 16 carbon atoms are liquids and those with 17 or more carbon atoms are solids. trong and not easily brokentive because the carbon-carbon single bonds in their molecules ar

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Reactions of alkanes

• Alkanes burn easily in air or oxygen

Alkanes burn in air or oxygen to form carbon dioxide and water as steam. They burn with clear, blue, non-smoky flames because they have a low ratio of carbon to hydrogen atoms in their molecules, All the carbon is converted to carbon dioxide and no unreacted carbon remains in the flames to make them smoky. The reactions are exothermic, producing large amounts of heat energy. eg. CH,(g) + 20,(8) -

CO,(g) + 2H,O(g) AH-ve

• Alkanes undergo substitution reactions with halogens

Under the correct conditions, alkanes undergo substitution reactions with halogens. In these reactions, the hydrogen atoms in the alkane molecules are replaced by halogen atoms such as chlorine or bromine. For the reaction to occur, energy in the form of light is required; ultraviolet light works best. The products of the halogenation of alkanes are known as haloalkanes or alkyl halides.