5- distillation of a reaction product and reflux

Question 1

procedure of oxidation of ethanol to ethanal (4 stages)

Answer 1

1.measure out 12cm^3 acidified potassium dichromate using measuring cylinder+pour into pear-shaped flask and cool this in an ice bath. Attach a thermometer.
2.measure out 2cm^3 ethanol and slowly add it dropwise into pear-shaped flask and shake
3.add a few anti-bumping granules and attach pear-shaped flask to delivery tube. Clamp flask into a beaker with cold water+attach a condenser
4.gently heat beaker of cold water to slowly distil off 5cm^3 of liquid distillate into a test tube immersed in an ice bath

Question 2

why does the test tube need to be kept cool in oxidation procedure

Answer 2

to avoid loss of volatile ethanol

Question 3

why is a boiling water bath used in reflux

Answer 3

controlled heating

Question 4

why are anti-bumping granules used

Answer 4

prevent large bubbles forming, allows for smoother boiling

Question 5

why should the system be open in reflux

Answer 5

sealing leads to build up of gas pressure, causing it to explode

Question 6

what is reflux used for+how does it work(3)

Answer 6

-heating organic mixtures for long periods
-condenser prevents organic vapours escaping by turning them back into liquids
-reactant vapours of volatile compound are condensed+returned to reaction mixture

Question 7

why should the water enter the condenser at the bottom

Answer 7

so condenser fills with water and more vapours can condense