RP5 - Distillation of a product from a reaction / Oxidation of Alcohols

Question 1

Reagents and conditions need for making aldehyde from a primary alcohol

Answer 1

Reagent - Acidified potassium dichromate (VI) solution

Conditions - Excess alcohol, warm gently, distil aldehyde out as it forms

Question 2

Why does water go in the bottom of the condensor

Answer 2

To go against gravity. This ensure the condenser remains full of water and allows more efficient cooling so more of the aldehyde condenses.

Question 3

Why are bunsen burners not used to heat the primary alcohols and what should be used instead

Answer 3

Organic chemical are highly flammable and could set on fire if we used a naked flame so electric heaters should be used instead.

Question 4

Why is the collection flask filled with ice

Answer 4

So more of the aldehyde condenses and therefore improves the yield

Question 5

What apparatus is needed for distillation when making aldehyde

Answer 5

Thermometer
Clamped round bottom flask
Electric heater
Liebig condensor
Collection flask
Anti-bumping granules
Bung

Question 6

Reagents and conditions for making a carboxylic acid from primary alcohol

Answer 6

Reagent - Acidified potassium dichromate solution

Conditions - Excess potassium dichromate, heat under reflux

Question 7

Why must a bung NOT be used when heating under reflux

Answer 7

Causes build up of gas pressure which could cause an explosion.

Question 8

Why are anti-bumping granules used in both reflux and distillation

Answer 8

Prevent formation of large bubbles.

Question 9

Equipment for reflux

Answer 9

Vertical condensor
Water out at top and water in at bottom
Clamps on condenser and flask
Round bottom flask

Question 10

Why is a thermometer needed when making aldehyde from distillation

Answer 10

So temperature does no go above boiling point of the aldehyde

Question 11

What is fractional distillation used for

Answer 11

Separating liquids with similar boiling points