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Oxidation of ethanol

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Introduction

Name ________________________ Date ________________ Introduction For this exercise you are given full instructions for the practical procedure and these must be followed exactly. It is however up to you to consider suitable safety procedures and to organise your time appropriately. You should also carefully consider what is the most effective way of handling the materials and apparatus in order to obtain the maximum reliability. The Oxidation of Ethanol Ethanol is a primary alcohol and can be oxidised to either an aldehyde or a carboxylic acid. CH3CH2OH + [O] CH3CHO + H2O CH3CH2OH + 2[O] CH3COOH + H2O The purpose of this experiment is to oxidise ethanol and then to test the product to determine whether it has been oxidised to ethanal or oxidised to ethanoic acid. Read through the procedure below before starting the experiment. You should comment on the hazard of the chemicals use din the experiment. Method To 6cm3 of water in the pear-shaped flask, add 2cm3 of concentrated sulphuric acid, and set up the apparatus as shown below, but with a stopper in place of the dropping funnel. Ensure that all of the glass joints are greased. 1. Make up a solution containing 5g of sodium dichromate in 5cm3 of water, add 4cm3 of ethanol and pour the mixture into the dropping funnel. ...read more.

Middle

Reacts violently with water and organic materials with evolution of heat (see Notes). Upon heating, irritating or toxic fumes (or gases) (sulfur oxides) are formed. For protection I wore protective gloves and safety glasses. * Potassium Dichromate - The substance is a strong oxidant and reacts with combustible and reducing materials. The solution in water is a weak acid. The substance is irritating to the skin and the respiratory tract. The substance is corrosive to the eyes. The substance may cause effects on the kidneys and liver, resulting in impaired functions. This was used in small amounts as an oxidising agent and it was not felt necessary to use it in the fire cupboard. For protection I wore protective gloves and safety goggles. * Universal Indicator Solution - Highly Flammable, Harmful by inhalation, in contact with the skin and if swallowed, Irritating to eyes. In most universal indicator solutions the solvent is ethanol; various indicators are dissolved in this to give the necessary pH-dependent colour changes. Ethanol is very flammable, so I should treat solution as a fire hazard. For protection I should wear safety glasses when using the solution and I should keep bottles of indicator solution away from naked flames. Small amounts of indicator solution can be flushed down a sink unless local rules prohibit this. ...read more.

Conclusion

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. ?? ?? ?? ?? BRAINTREE TERTIARY COLLEGE AS LEVEL CHEMISTRY ASSESSED PRACTICAL - SKILL I - 1 - ...read more.

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