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Reaction of Alkane, Alkene & Alkyne Essay

Apparatus: dropper, test tube, hot plate
Chemical reagents: bromine, toluene, cyclohexane, cyclohexene, acidified KMnO4, dichloromethane Method
A. Bromine test
1.6 clean and dry test tube were taken and were labelled them A until F 2.1ml of dichloromethane were placed into each test tube
3.1 ml of cyclohexane were placed into tubes A and B,1 ml cyclohexene were placed into test tube C and D,1ml toluene to test tube E and F 4. 5 drops of bromine water were placed into each test tube

5. Test tube A, C and E were placed in the dark; test tube B,D, and F under the sunlight. All the tubes were leaved for 10 minutes B. Oxidation Test with Acidic KMnO4
1. 3 clean and dry test tubes were labelled
2. 1ml cyclohexane, cyclohexene and toluene were placed into each test tube respectively 3. Few drops of acidic KMnO4 were placed into each test tube 4. The test tube were heated in a water bath

5. Observation were recorded
5. Observation
Reaction with bromine water
Test| Observation| Inference|
1ml of cyclohexane + bromine water + sunlight| Orange colour changes to colourless when exposed to light| Alkane present| 1ml of cyclohexane + bromine water + dark| No colour change| Alkane present| 1ml of cyclohexene + 3 drops of bromine water + shaking| Decolourisation of bromine water. No colour change| Alkene present|

Reaction with aqueous potassium permanganate
Test| Observation| Inference|
2ml of cyclohexane + 2 dropsKMnO4 + shaking| No colour change with the addition of aqueous KMnO4| Presence of Alkane| 2ml of cyclohexene + 2 dropsKMnO4 + shaking| Colour changes to colourless with brown precipitate| Presence of Alkene|

Reaction with potassium permanganate and aromatic compound
Test| Observation| Inference|
1ml of toluene + 2ml of dilute KMnO4 + shaking| Two layers formed. Pale violet and deep violet colour formed| Aromatic compound present|

6. Discussion
Although all hydrocarbons contain carbon and hydrogen, they have different properties. The most common property used to distinguish these hydrocarbons is based on their reaction with other compounds. Fromm the first experiment when bromine water was added to cyclohexane and shaken and was also kept in the dark, no colour change was observed which indicated presence of an alkane. But when this same mixture was exposed to the sunlight there was an observable colour change . These observable characteristics are very specific of alkanes which undergo substitution reaction under sunlight.

Also when bromine water was added to cyclohexene, the bromine water decolourised rapidly under room temperature with evolution of hydrogen bromide gas which indicated the presence of an alkene as they undergo addition reaction under these conditions. In the second experiment when drops of KMnO4 solution was added to cyclohexane and shaken there was no observable reaction which indicated the presence of an alkane as alkanes are unreactive towards oxiding agents.

However when the same drops of KMnO4 solution was added to cyclohexene, there was a decolourisation of the KMnO4 solution colour which is characteristics of alkenes as they readily oxidised at room temperature. In the final experiment, aqueous potassium permanganate was added to toluene which formedtwo layers of colour. A pale violet colour formed above a deep violet colour showing the presence of aromatic compound

SGS 1054
Practical 2
Reaction of alkane, alkene & alkyne

ID: 012013O50899
Programme: BBI

Practical 3 SGS 1054
Title: Classification of alcohols

1. Objective:
Classify primary, secondary and tertiary alcohols.

2. Apparatus: dropper, test tube, test tube rack,

3. Chemical reagents: n-butanol, 2-butanol, t-methyl-2-propanol, lucas reagent, concentrated H2SO4, Na2Cr2O7

4. Method:
A. Oxidation Test

1. Three small test tubes was prepared in tube rack.
2. 1ML of Na2Cr2O7 was prepared and poured into labelled test tube. 3. Drop of concentrated H2SO4 was poured into test tube from 2nd step (*precaution: handling of H2SO4 MUST be in FUME HOOD!!.) 4. Drops of n-butanol was added and heated

5. The colour changes was observed
6. Observe the colour changes.
7. Result was recorded

Lucas Test

1. Three small test tubes were prepared as above.
2. 0.5 mL of the test alcohol was added to each test tube. 3 mL of the Lucas reagent was added. The mouth of test tubes was covered using a small cork. 3. Changes was observed
4. Steps were repeated to all three classes of alcohol.


Chemical| Lucas test| H2SO4, Na2Cr2O7 /H+|
t-methyl-2-propanol| Solution turns cloudy immediately| Orange colour solution maintained| 2-butanol| Solution turns cloudy immediately| Green solution formed| n-butanol| Colourless solution formed| Turn to green solution|

1) The alcohols are classified as
Primary (1°),
Secondary (2°)
Tertiary (3°)
2) Alcohols undergo oxidation to give aldehydes ,ketones, or carboxylic acids, or they can be dehydrated to alkenes. As one moves from primary to secondary to tertiary alcohols with the same backbone, the hydrogen bond strength, the boiling point, and the acidity typically decrease.

SGS 1054
Practical 3
Title: Classification of alcohols

ID: 012013O50899
Programmed: BBI

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