Identifying an Unknown Compound

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Identification of an Unknown Organic Compound

Ensure a lab coat, safety glasses and gloves are worn during the experiments and work in a ventilated area. For all experiments test tubes and pipettes will be required.

ALKENES:

Alkenes contain a double carbon-carbon bond.

APPARATUS: Unknown compound, bromine water.

METHOD: Add 5 drops of bromine water to a test tube containing 1cm3 of the unknown and shake.

OBSERVATION: Bromine water will decolourise from orange.

EXPLANATION: The alkene decolourises bromine water and produces 1,2-dibromoethane. The double bond allows electrophilic addition reactions to occur.

HAZARDS: Bromine vapour released from the water is 1^harmful^1 (see appendix).

ESTERS:

Esters are sweet- smelling products from reactions between carboxylic acids and alcohols.

APPARATUS: Unknown compound, phenolphthalein, water bath, NaOH.

METHOD:  1Add 5 drops of phenolphthalein and NaOH to the unknown in a test tube and shake. Then heat the solution in a water bath.1 

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OBSERVATION: A pink colour will appear once the indicator has been added and when heated the pink colour will disappear.

EXPLANATION: This reaction is the hydrolysis of an ester; the pink colour disappears as the ester has completely reacted with NaOH and forms the salt of sodium.

HAZARDS: Phenolphthalein- 2^irritant^2. NaOH- 1^harmful^1 and 3^corrosive^3.

PHENOLS:

Phenol has the formula of C6H5OH, its structure consists of an OH group attached to a benzene ring.

APPARATUS: Unknown compound, ferric chloride (iron III chloride).

METHOD: Add 5 drops of ferric chloride to the unknown.

OBSERVATION: An intense violet-purple colour ...

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