ALCOHOL

Question 1

REFLUX

Answer 1

Reflux means you can increase the temperature of an organic reaction to boiling without losing volatile solvents, reactants or products.

Question 2

how to get aldehydes, carboxylic acid and ketones

Answer 2

for aldehydes - distillation
for carboxylic acid and ketones - reflux.

Question 3

oxidising primary alcohol to aldehydes

Answer 3

distillation
- gently heat ethanol with potassium dichromate solution and sulfuric acid in atest tube.
- to just get the aldehyde, gently heat excess alcohol with controlled amount of oxidising agent in the distillation apparatus. ( aldehyde has lower bp than alcohol)

Question 4

oxidising further into carboxylic acids

Answer 4

• heated under reflux.
• reflux means heating the mixture upto boiling without loosing any volatile solvents, reactants or products.
• any vapourised compounds are cooled, condensed and drip back into the reaction mixture. aldehyde stays in the reaction and is oxidised to carboxylic acids.

Question 5

oxidising into ketones ( 2nd degree alcohol)

Answer 5

excess acidified potassium dichromate
heat the reaction
to prevent lossing ketones, we use a condenser. ( liebig condenser)
water in - to keep the condenser cool and for a constant supply of tap water.

Question 6

chemical test for alcohol

Answer 6

add acidified potassium dichromate- if the sloution becomes green - then primary or secondary alcohol - if the solution stays orange - tertiary alcohol

Question 7

elimination or dehydration of alcohol

Answer 7

alkene and water is formed.
acid catalysed e,limination - uses conc. sulphuric or phosphoric acid for the reaction.

Question 8

hydration of alkene

Answer 8

steam hydration of ethene. ethene can be hydrated by steam at 300 degree celsius and apressure of 60 atm. solid phosphoric acid catalyst

Question 9

fermentation

Answer 9

fermentation is an exothermic process, carried out by yeast in anaerobic conditions.

Question 10

conditions required by fermentation

Answer 10

yeast
30-40 degree celsius.