identification of an organic unknown

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Identification of an organic unknown

Aim:

My aim for this investigation is to identify doing simple chemical tests of different organic compounds containing one of the following functional groups such as:

* Alkenes

* Primary alcohol

* Tertiary alcohol

* Aldehyde

* Ketone

* Carboxylic acid

* Ester

* Phenol

I will take each of the functional group and identify a test to see if the functional group is present in a unknown organic compound.

Alkenes:

Alkenes are unsaturated hydrocarbons which at least have 1 carbon-carbon double bond (C=C). They have the general formula of CnH2n with the structural formula of: CnH2n . They have a planar shape with bond angles of 120. (http://en.wikipedia.org/wiki/Alkene)

The test I am going to do for alkene to identify if the alkene is present or not is a bromine water test, which means if the alkene is present it will decolourised bromine water.

Method:

* First I will add few drops of bromine water into a test tube.

* Then I will add few drops of unknown organic compound.

* Then I will shake the test tube.

If the alkene decolourized bromine water this means that alkene is present. The colour will change from orange to colourless.

Apparatus:

i. Test tube

ii. Bromine water

iii. Unknown organic compound

Equation:

(http://www.bbc.co.uk/schools/gcsebitesize/img/ch01008.gif)

Alcohols:

Alcohols are compounds in which one or more hydrogen atoms in an alkane have been replaced by an -OH group.

Primary alcohols:

In a primary (1°) alcohol, the carbon which carries the -OH group is only attached to one alkyl group.

Test:

Primary alcohols can be oxidised to either aldehydes or carboxylic acids depending on the reaction conditions. The oxidising agent used in these reactions is normally a solution of sodium or potassium dichromate (VI) acidified with dilute sulphuric acid. If oxidation occurs, the orange solution containing the dichromate (VI) ions is reduced to a green solution containing chromium (III) ions. (http://www.chemguide.co.uk/organicprops/alcohols/oxidation.html)
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Primary alcohols are oxidised on heating with acidified aqueous potassium dichromate. If the colour change from orange to green this means that primary alcohol is present.

Apparatus:

* Test tubes

* Unknown organic product

* Acidified potassium dichromate

Equation:

CH3CH2OH + [O] CH3CHO + H2O

([O] Acts as an oxidising agent)

Tertiary alcohols:

Tertiary alcohols aren't oxidised by acidified sodium or potassium dichromate (VI) solution. To find out if tertiary alcohols is present or not I will do a Lucas test.

Lucas reagent:
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