Test For Alkene

Alkenes are called unsaturated compounds. They contain at least one carbon-carbon double bond which displaces two hydrogen atoms and so do not have the maximum number of hydrogen atoms per carbon atom.

Alkanes on the other hand are called saturated compounds. They contain only single bonds and the maximum number of hydrogen atoms per carbon atom.

The presence of the double bond in alkenes makes them more reactive than alkanes. This higher reactivity of the alkenes over alkanes allows us to distinguish them. A simple test with bromine water can be used to tell the difference between an alkane and an alkene. An alkene will turn brown bromine water colourless as the bromine reacts with the carbon-carbon double bond. In fact this reaction will occur for unsaturated compounds containing carbon-carbon double bonds. An alkane undergoes no reaction with bromine water and therefore there is no colour change.

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Functional group between Alkanes and Alkenes

Alkanes: (single bond) (C-H)

Alkenes: (double bond) (C=H)

Fuels used in cars often have sulfur compounds removed.

Fuels used in cars often have sulfur compounds removed.

Explain how the combustion of these fuels in car engines still leads to the formation of acid rain?

The pressure and temperatures inside the cars engine cause the oxygen and hydrogen in the engine to react to create oxides of nitrogen. The two pollutants made inside the engine are NO and NO2. These two are grouped together and called NOx. NOx gases in the air cause acid rain and react with other pollutant in the air to create photo chemical smog.