The test tube was haken before the test tubes was placing in the boiling water bath in 3 minutes. 4. After the boiled process, it was continue to whiff the vapor released from the test tube. 5. Record the smell produced. Result: A. Combustion of Alcohols: Types of alcohols I Colour flame I Luminosity I Methanol I Less-blue colour formed I Less intensity I Ethanol I Wide-blue with little yellow colour I High intensity of blue colour Table 1 : the result from the combustion of methanol and ethanol B. Oxidation with Potassium Permanganate: Time required for oxidation of methanol by Potassium Permanganate Solution,
KMn04 : Tube A: Alkaline solution Tube B: Acid solution Tube C : Neutral solution Tube D : Water C. Esterification Observation: pungent smell produced Question: 1 . Write and balance the equation for the complete combustion methanol? 2. Name the ester product formed in experiment C? Describe the odor? The ester produce is acyl ethanoate. The produced is fruity smell. 3. Write the equation to illustrate formation of ester above from ethanol and acetic acid? Discussion: In this experiment, there are three types of test involving alcohols which are ombustion, oxidation of alcohol and the esterification reaction.
There are many reactions involving of alcohols which are elimination, substitutions, oxidation and esterification and also combustion. For combustion reaction, this is the direct reaction which is from the reactant to the product. In experiment 1, there a two type of alcohol which are methanol and ethanol. The combustion of these alcohol are usually different in molecular structure, boiling point and their melting point. In theory, the higher the number of carbon in molecule, the higher the melting point nd boiling point of an alcohol as well as their energy needed.
The energy needed for this reaction is different because of their carbon contain in the molecule. When compared to the between the alcohols the methanol are much more smaller in number of molecule than the ethanol which is number of carbon is two. When these two alcohols are burn in air, it will react with oxygen which is can be form in the equation: 2CH30H(l) + 302(g) 2C02(g) + 4H20(l) From the equation, two mol of methanol is required when react with three mol of oxygen gas which will roduce two mol of carbon dioxide and four mol of water.
When they undergoes reaction of oxygen the methanol will produce a less colour of blue flame and less intensity of the flame produce. While, when the ethanol was burn in oxygen it will produce wide-blue with little yellow colours of flame and the luminosity produce are high intensity of blue colour. This different between this combustion because the number of carbon contain in alcohols which affect the need of heat required to break the bond between the molecules. The oxidation of alcohols which are made by divided into three test tubes.
The first one was mixture between methanol with 1 drop of 10% NaOH solution. While for the second test tube was mixture between methanol with dilute sulfuric acid. The fourth test tube was act as reference tube. For the first tube, the reaction between methanol with sodium hydroxide was an alkaline solution. Actually, the alcohols are normally only very weakly acidic so they will not react with bases such as NaOH. That’s why the time for methanol oxidized in NaOH solution was taking more than 30 minutes and the potassium permanganate solution does not decolorized.
For test tube 2, the methanol was mixed with sulfuric acid. The methanol that was used in this experiment was a primary alcohol. The oxidation for primary alcohol with Cr03/ H2S04 will produced carboxylic acid. The potassium permanganate solution will become yellowish. The time taken to become yellowish approximately around 8. 29 seconds. The potassium permanganate solution is an inorganic chemical compound with the formula KMn04. It is a salt consisting of K+ and Mn04- ions and most suitable for oxidization agent. The For the reaction 3, the reactions are between the ethanol and acetic acid.
This reaction are the esterification reaction which is involve an acid and alcohols. The esterification reaction of esterification is reversible and proceeds slowly but the rate of esterification is increased by the presence of 3 drop of sulphuric acid as the catalyst in the reaction. Concentrated of sulphuric acid removed the water produced and help to push the equilibrium towards the product side of the equation. Excess alcohol will also force the equilibrium to the right. The first step involve the protonation of the carbonyl oxygen, followed by the nucleophilic attack of the alcohol, inished off with the loss of the proton.
Again protonation of the one of the -OH group, followed by the loss of water yields the protonated ester. Loss of a proton yields the ester. The ester produced is ethyl ethanoate.
