For personal protection protective gloves and safety goggles were worn during the experiment. Because of the chemicals used, a window was left open during the experiment in order to assure ventilation. Observations Ethanol has been oxidised using potassium dichromate (VI) as an oxidising agent in dilute acid. Initially, ethanol has been oxidised to form an aldehyde, but if the oxidising agent is used in excess, further oxidation to the carboxylic acid occurs. Ethanol has been oxidised to give ethanoic acid, by heating under reflux potassium dichromate (VI).
Before starting the experiment I ensured that the desk was clean and that all the apparatus and all the glass joints were greased and cleaned. I checked the hazard cards and read carefully through each chemical notes I was going to use in the experiment. When setting up the apparatus, I decided to use clips in order to seal all the joints, for safety procedures and to obtain the maximum reliability. After carefully setting up the apparatus, I accurately measured 5 g of Sodium Dichromate using a balance and wearing protective gloves.
I also measured 4 cm of Ethanol and 2 cm of concentrated Sulphuric Acid wearing protective gloves and safety goggles. As the oxidation of Ethanol is an exothermic reaction, during the experiment, I accurately measured the temperature, using an appropriate thermometer, in order to obtain a reliable product. The initial temperature was 21 i?? C and it kept increasing until 95 i?? C. At this temperature, I decided to turn off the heating and stop the experiment, as the boiling point of the water is 100 i?? C and at this temperature I will get water instead of an aldehyde or a carboxylic acid.
I added the mixture containing the Ethanol at such a rate as to maintain the boiling of the mixture in the pear shaped flask. During the distillation process I wore protective gloves and safety goggles, for personal protection. Conclusion Use your results to decide whether an aldehyde or a carboxylic acid had been formed during this experiment. Explain how you made your decision. After collecting enough distillate to proceed with the two tests, I measured 5 cm of 2, 4 – dinitrophenylhydrazine using an adequate measuring cylinder and then put it into a test tube.
I cautiously added 5 drops of the distillate wearing protective gloves and safety goggles. I observed a bright orange or yellow precipitate which shows the presence of the carbon-oxygen double bond. Therefore an aldehyde has been formed. For the second test, I put 5 drops of the distillate in the test tube and then added another 5 drops of universal indicator solution. Universal Indicator solution is a mixture of compounds that take on a variety of colors at different pHs. pH is a quantitative measure of the acidity or basicity of a solution.
The more acidic a solution is, the lower its pH. The pH scale runs from 0 to 14. pHs less than 7 are acidic, pHs greater than 7 are basic and a pH of 7 is neutral, neither acidic nor basic. It ranges from red (a strong acid) to a deep violet (a strong alkali). Universal indicator turns neutral solutions green. I observed an orange precipitate and which had a pH of 3, demonstrating that an acid group has been formed. The second test shows that ethanoic acid has been formed, and therefore a carboxylic acid has been formed during the experiment.