Ethanal Experiment(Complete)

Question 1

What is the formula for ethanal?

Answer 1

CH3CHO

Question 2

What is the boiling point of ethanal?

Answer 2

Boils at around 20C.

Question 3

How are aldehydes produced?

Answer 3

Made by the oxidation of primary alcohols.

Question 4

What is the smell of ethanal?

Answer 4

Smell of rotten apples.

Question 5

Where is this smell of ethanal commonly scented?

Answer 5

On heavy drinkers due to the oxidation of ethanol to ethanal in the liver.

Question 6

Describe aldehydes solubility.

Answer 6

Short chain members are soluble in water due to the polar carbonyl group (C=O).
Long chain members are insoluble in water.

Question 7

Describe a test for aldehydes.

Answer 7

Mix Fehling's 1 and 2 solutions.
Add the aldehyde.
Heat gently using a water bath.
Will turn from blue to red precipitated.
Cu2+ + e- = Cu+
The copper ion is reduced as there is a gain of an electron.

Question 8

Describe another test for aldehydes

Answer 8

Mix aldehyde with ammoniacal silver nitrate( Tollen’s Reagan).
Heat.
A silver mirror is produces on the test-tube.
The test tube must be clean or black.
Ag+ + e- = Ag
The silver ion is reduced as there is a gain of electron.

Question 9

What is the formula for propanone.

Answer 9

CH3COCH3.

Question 10

How are ketones made.

Answer 10

By oxidising secondary alcohols.

Example- Propan-2-ol is oxidised to produce propanone.

Question 11

How do you oxidise a substance?

Answer 11

Using acidified dichromate and heat.

Question 12

What is a property of ketones?

Answer 12

They do not oxidise any further.

Question 13

How do you reduce a substance?

Answer 13

Using H2, Nickel (Ni) catalyst and heat.

Question 14

Describe and account for the colour change which is observed during the addition of the ethanol and sodium dichromate (VI) 
solution to the hot acid. (9)

Answer 14

The orange solution added to the colourless liquid becomes green.
Cr2O7- is reduced to Cr3+.