identifcation of and organic unknown

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Thomas Stirling 13jn

Candidate number: 2671

Identification of an organic unknown

Plan

Introduction

In this investigation I will get a number of unknown organic compounds to which I have to identify using a number of simple chemical tests. The flow-chart below shows these simple tests that I will use to identify the functional groups of the unknowns.

General safety procedures

Always wear gloves and goggles when handling any unknown because some materials could be corrosive or an irritant. Be careful when disposing organic materials insure there is an organic waste beaker or bucket available.

 1. Test unknown with acidified potassium manganate.

THEROY: Manganate (VII) ions are a strong oxidising agent, and in the first instance oxidise ethene to ethane-1,2-diol causing the colour change from purple to colourless. The equation is as follows; C2H4 + H2O + {O}               C2H6O2

EQUITMENT: pipettes,

                   Test tube,

                   Beaker of warm water.

SAFETY: follow general safety procedures.

PROCEDURE: Add 1cm3 of potassium manganate to a test tube also add 1cm3 of sulphuric acid  to the test tube and also add a few drops of the unknown, final place the test tube in a beaker of warm water.

OBSERVATIONS: A colour change to colourless indicates an alkene, any other colour change shows Alcohol, aldehyde, ketone, carboxylic acid, ester or phenol.

2. Test unknown with universal indicator.

THEROY: universal indicator is a mixed indicator, several indicators with different pH values. When added to different solutions of different pH different indicators change colour, the colour you see is a result of the different indicators mixing together. The colours have been recorded and linked to a colour chart.

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EQUITMENT: universal indicator,

                    Pipette,

                   Test tube.

SAFTETY: always follow general safety procedures, and be aware that universal indicator is dangerous.

PROCEDURE: Add several drops of the unknown substance to universal indicator inside a test tube using a pipette.

OBSERVATIONS: A colour change to red indicates either a carboxylic acid or phenol is present. Any other colour change shows alcohol, aldehyde, ketone or ester.

 3. Test unknown with bromine water.

THEROY: Aqueous phenol decolourises bromine water to form a white precipitate of 2,4,6-tribromophenol, the reaction takes place as follows

The bromine water acts as ...

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