The oxidation of Ethanol.

• Place 5 drops of the distillate in a test tube and add a tiny amount of sodium carbonate.

Test 2 – Testing for the presence of an acid group to find out whether ethanoic acid has been formed.

• Place 5 drops of the distillate in a test tube and add 5 drops of universal indicator solution.

Safety

The chemicals used in the experiment were-

• Ethanol
• Ethanal
• Ethanoic Acid
• Sodium Carbonate
• Sodium Dichromate
• Sulphuric Acid
• Universal Indicator

The above chemicals did have some hazards when in the context of this experiment. Due to these hazards I wore a lab coat to protect from things like the Na2Cr2O7, which stains, also I wore protective glasses to prevent things from entering my eyes. Below are the hazards.

Ethanol –

        Highly flammable above 13°C causing a narcotic effect if inhalation of the vapour occurs.

        Toxic

        Dangerous with → Oxidising Agents – incontrollable reactions

                                                                        take place

                 → Bromine

                              → Mercury (׀׀)

                              → Silver Nitrate

                              → Platinum

                              → Potassium

Ethanal –

        Extremely flammable above -27°C

        Harmful – risk of irreversible effects

        Dangerous with sulphuric acid – evident polymerisation reaction

                                                  May occur

Ethanoic Acid –

        Corrosive → Severe Burns

                       → Flammable above 40°C

                         → Vapour irritating to the respiratory system

Sodium Carbonate –

        Irritant to → Eyes

                       → Skin

                    → Respiratory System

Sodium Dichromate –

        Very Toxic → Cause cancer if inhaled

                          → Harmful if swallowed

                         → Harmful if in contact with skin

                         → Ulceration may occur on damaged skin -

                              Sensitisation by skin contact

        Danger to environment – Very to toxic to aquatic environment may

                                        Cause long-term adverse effects

Sulphuric Acid –

        Very corrosive – cause severe burns

        Dangerous with → Sodium – dangerous reactions can take place

                                → Water – Vigorous reaction when the

                                                  Concentrated acid is diluted.

Universal Indicator –

        When in the context of this experiment universal indicator has no relevant hazard’s.

Observations

        During the course of the experiment I wrote down a few observations including smells, colours, effervescence etc. Below are the observations for the experiment in the order of observing them.

        At the very beginning when I added the concentrated sulphuric acid to the water I noticed as I held the pear shaped flask that it began to heat up. This meant that the reaction between the acid and the water was an exothermic one meaning it gave out heat to the surroundings as energy was released.

        The next step involved mixing of the sodium dichromate, which was a bright orange solid, and the water with the ethanol, which was a clear solution. The reason for this was because the reaction between the two solutions caused it to continue boiling. The resulting solution was a bright orange colour due to the sodium dichromate. The resulting solution also had a vinegar smell to it.

        The concentrated sulphuric acid and water solution only needed a small blue flame under it for a short period before it began to boil rather vigorously. At this time I began to gradually add the orange solution so as to maintain the boiling of the ethanol and water solution. As soon as the orange solution mixed with the sodium dichromate & water solution it turned a dark green. This was all due to the redox reaction that was taking place.

        During the test on the distillate some observations were made, such as in the first test with the sodium carbonate, a white powder. When it was added to the distillate gentle effervescence occurred. This bubbling was CO2 being released from the sodium carbonate.

        During the second test universal indicator was added to the distillate. This resulted in a very bright red solution, means that the distillate is a strong acid (a 1-2 on the pH scale).

Conclusion

        Therefore to conclude my experiment I can deduce from my results that oxidising ethanol produces ethanoic acid. This was proven from my two tests. Another test was advised but lack of the proper equipment and chemicals prevented this. Instead it was replaced with the sodium carbonate test.

The sodium carbonate test proves that the ethanol was oxidised into ethanoic acid because when added to the distillate effervescence occurred. This would only have occurred if the distillate were ethanoic acid. If it were ethanal then it would not have fizzed. The equation for this is-

2CH3COOH  +  Na2C03                               2CH3COOˉ Na+  +  C02  +  H2O

                                                Effervescence

The universal indicator test also proves that the distillate is an acid. This is because when added to the distillate it turns a bright red, which means it is a 1 on the pH scale. This would not have happened if ethanal was the distillate.

The colour change during the experiment was due to the redox reaction-taking place. The orange dichromate ion (Cr2 O7² ˉ) was reduced to a green chromium (ااا) ion (Cr³+).