The purpose of this experiment is to oxide ethanol a primary alcohol and then to test the product to determine whether it has been oxidised to ethanal an aldehyde: CH3CH2OH + [O] → CH3CHO + H2O

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The Oxidation Of Ethanol

Introduction

The purpose of this experiment is to oxide ethanol a primary alcohol and then to test the product to determine whether it has been oxidised to ethanal an aldehyde:

CH3CH2OH + [O] → CH3CHO + H2O

Or whether it has been oxidised to ethanoic acid a carboxylic acid:

CH3CH2OH + 2[O] → CH3COOH + H2O

In theory, ethanal should be produced as a product. This is because you will be distilling the ethanal as it forms so it isn’t exposed to the acidified sodium dichromate to become a carboxylic acid. Therefore the CHO group of ethanal will not be oxidised further to the COOH group of ethanoic acid.  

Observations

As the sodium dichromate and ethanol solution in the dropping funnel were slowly added to the concentred sulphuric acid in the pear shape flask, the colour of the solution gradually changed from orange to green as more of the dichromate and ethanol was added. This was because a reaction took place, so the dichromate – Cr2O72- got reduced to form chromium ions – Cr3+ and the ethanol got oxidised.

When the sodium dichromate and ethanol solution was added to the concentred sulphuric acid in the pear shape flask, I noticed that it began to bubble and out give out heat. This meant that there was an exothermic reaction between the acidified sodium dichromate and ethanol that caused it to continue boiling on its own.

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After the solution had been bubbling for a while a colourless distillate began to distil over the distillation funnel and was collected into a boiling tube which was held in a beaker with an ice and water mixture in so if the ethanal was produced, it didn’t just evaporate away because of its low boiling point.  

When the 5 drops of the colourless distillate were added to the 5cm3 of 2, 4 dinitrophenylhydrazine to test for an aldehyde, within approximately 2 minutes an orange precipitate formed in the yellow/orange solution. This was because a carbonyl group was ...

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