Physical Properties

Question 1

All straight carboxylic acids up to 10 carbons are what?

Answer 1

Liquid at room temperature

Question 2

What’s the exception to the 10 carbon rule?

Answer 2

Ethanoic acid (glacial acetic acid) which freezes to an ice-like substance below 17 degrees

Question 3

Will carboxylic acids have an odour? If so describe it

Answer 3

Yes, it will have a sharp pungent odour

Question 4

What is the boiling point range for the liquid carboxylic acids (under 10 carbons)?

Answer 4

100-250 degrees

Question 5

Give reasoning to the property: “smaller molecules (less than 4 carbons) are completely miscible in water”

Answer 5

They are completely miscible in water due to the formations of hydrogen bonds with water

Question 6

What happens to the solubility of the hydrocarbons after the 4 carbon mark?

Answer 6

It lowers

Question 7

Which carboxylic acids can be dissolved in suitable organic compounds?

Answer 7

All of them

Question 8

What happens to highly polar carboxylic acid molecules when in liquid phase and in non-aqueous solvents? Give an example

Answer 8

The molecules dimerise, eg CCl*4 forming two hydrogen bonds between each pair of molecules

Question 9

What does this extra degree of hydrogen bonding do to the boiling point of the carboxylic acid when comparing it to corresponding alcohols?

Answer 9

It raises it by about 20 degrees

Question 10

What happens to the dimers in aqueous solutions?

Answer 10

They dissociate