Flow Chart Showing Tests to Identify All 8 Chemicals
Background Information & Methods for Testing:
Alkenes5&6:
Alkenes are hydrocarbons which are formed by cracking larger hydrocarbons. Unlike alkanes, alkenes are unsaturated due to the double bond between the carbon atoms. They have the general formula CnH2n.
An example of an alkene is ethene. It has the structural formula C2H4.
Molecular Formula: C2H4 = CH2=CH2
Structural Formula of Ethene:
Double bond between Carbon atoms
Hydrogen atoms
To test for an alkene, I will mix the unknown organic compound with bromine water. The solution will turn from orange to colourless in the presence of an alkene. This will prove that a double bond is present; therefore the liquid was an alkene. The double bond between the carbon atoms will open up and bromine will be added on forming a haloalkane, for example Bromoethane.
Add 5cm3 of the unknown liquid into a boiling tube. Then add 2cm3 of Bromine water to the liquid and mix well. If the solution decolourises, it will indicate that the unknown liquid was an alkene.6
Equation for the reaction:
Phenols4:
Phenols are made of a benzene ring attached to a hydroxyl group. They have a formula C6H5OH. The Benzene ring makes the OH group more acidic in Phenol than it is in Alcohol. However, Phenols are not as acidic as carboxylic acids.
Molecular formula of Phenol: C6H5OH
Structural Formula of Phenol:
OH group
Benzene Ring
To test for phenols, the unknown substance will react with bromine water, decolourising the solution and forming a white precipitate.5
Add 5cm3 of the unknown substance into a boiling tube. Then add 2cm3 of Bromine water to the solution and mix well. The solution should decolourise and a white precipitate should start to form. To confirm that the unknown substance is a phenol, add 1cm3 of Iron (III) Chloride to the solution and mix. The solution should turn purple, confirming the unknown substance is a phenol.5
Background Information & Methods for Testing:
Alkenes5&6:
Alkenes are hydrocarbons which are formed by cracking larger hydrocarbons. Unlike alkanes, alkenes are unsaturated due to the double bond between the carbon atoms. They have the general formula CnH2n.
An example of an alkene is ethene. It has the structural formula C2H4.
Molecular Formula: C2H4 = CH2=CH2
Structural Formula of Ethene:
Double bond between Carbon atoms
Hydrogen atoms
To test for an alkene, I will mix the unknown organic compound with bromine water. The solution will turn from orange to colourless in the presence of an alkene. This will prove that a double bond is present; therefore the liquid was an alkene. The double bond between the carbon atoms will open up and bromine will be added on forming a haloalkane, for example Bromoethane.
Add 5cm3 of the unknown liquid into a boiling tube. Then add 2cm3 of Bromine water to the liquid and mix well. If the solution decolourises, it will indicate that the unknown liquid was an alkene.6
Equation for the reaction:
Phenols4:
Phenols are made of a benzene ring attached to a hydroxyl group. They have a formula C6H5OH. The Benzene ring makes the OH group more acidic in Phenol than it is in Alcohol. However, Phenols are not as acidic as carboxylic acids.
Molecular formula of Phenol: C6H5OH
Structural Formula of Phenol:
OH group
Benzene Ring
To test for phenols, the unknown substance will react with bromine water, decolourising the solution and forming a white precipitate.5
Add 5cm3 of the unknown substance into a boiling tube. Then add 2cm3 of Bromine water to the solution and mix well. The solution should decolourise and a white precipitate should start to form. To confirm that the unknown substance is a phenol, add 1cm3 of Iron (III) Chloride to the solution and mix. The solution should turn purple, confirming the unknown substance is a phenol.5
