RPA oxidation of ethanol

Question 1

what is oxidation

Answer 1

loss of electrons

if an element is oxidised, it’s oxidation number increases

Question 2

what is distillation

Answer 2

distillation is a technique where the heating of a liquid to create a vapour is cooled by a condenser, causing the gas to condense into a liquid and drip into a separate flask

the different substances will be separated by boiling point/ volatility

Question 3

what equipment is used for distillation?

Answer 3

quickfit apparatus
pear shaped or round-bottomed flask with a Liebig condenser, still head, stopper, receiver adaptor, fitted with a thermometer and collection vessel

Question 4

what happens when you oxidise ethanol by distillation?

Answer 4

ethanol is distilled with acidified potassium dichromate and is oxidised into an aldehyde, ethanal

this is shown by a colour change from orange to green

Question 5

what is the equation for the oxidation of ethanol to ethanal

Answer 5

CH3CH2OH +[O] –> CH3CHO + H2O

Question 6

how do you use laboratory equipment to heat under reflux

Answer 6

quickfit apparatus is used to heat a substance under reflux

the substance is boiled in a pear shaped or round bottomed flask
as it evaporates, it is cooled by the water in the liebig condenser and so condenses back into a liquid and drips back down into the flask to be heated again

Question 7

why is heating under reflux used

Answer 7

allows heating for a long period of time
prevents the flask from boiling dry
prevents volatile reactants/ products escaping
ensures even heating

Question 8

why are anti-bumping granules used when heating under reflux/ in distillation

Answer 8

to allow smooth boiling

they prevent the appearance of bubbles caused by vapour in the hot liquid which would cause splashing up the flask

Question 9

what happens when you oxidise ethanol under reflux

Answer 9

ethanol is refluxed with acidified potassium dichromate and is oxidised into a carboxylic acid, ethanoic acid
this is shown by a colour change from orange to green

Question 10

what is the equation for the oxidation of ethanol to ethanoic acid

Answer 10

CH3CH2OH + 2[O] –> CH3COOH +H2O

heated under reflux with either h2so4/k2cr2o7

Question 11

what are some potential hazards and risks in the lab

Answer 11

bunsen burner –> may burn you –> keep away from flammable chemicals and away from desk edge
ethanol –> flammable –> wear eye protection, keep away from desk edge and from an open flame
potassium dichromate –> health hazard and irritant
glassware –> break and cut you –> handle with care and keep away from desk edge