Carbon Chemistry - Properties (eg melting/boiling points, solubility)

Question 1

The melting trends of hydrocarbons

Answer 1

The melting and boiling points of hydrocarbons increases as the carbon chain length increases.

Question 2

Why is it that as carbon chain length increases the melting/boiling points increase too?

Answer 2

In order to change a substance’s state, forces of attraction between neighbouring molecules must be overcome as the molecules must be pushed apart to change states.

The longer the carbon chain, the greater the force of attraction between the molecules, meaning that more energy is required to overcome these forces in order separate the molecules to change the substance’s state.

Question 3

What are two liquids that do mixed are referred to as?

Answer 3

Miscible

Question 4

Solubility of alkanes, alkenes and alcohols?

Answer 4

Alkanes and alkenes are INSOLUBLE and IMMISCIBLE in water.

Alcohols are soluble and immiscible.

Question 5

Why are alkanes and alkenes insoluble in water but alcohol is?

Answer 5

This is because a solute will dissolve in a solvent if the forces of attraction between the solute and solvent are strong enough to overcome the forces of attraction between the solute molecules.

A solute will NOT dissolve in a solvent if the forces of attraction between the solute and solvent are WEAKER than the forces of attraction between the solute molecules.

Question 6

How to separate a solute from solvent using distillation?

Answer 6

The two substances must have different boiling points.

• Evaporate the solution and make sure it doesn’t boil
• the substance with the lower point will evaporate first, turning into a gas and leaving the water behind as a liquid. -The gas travels through the delivery tube to be collected and cooled back into a liquid.

Question 7

Are alcohols basic?

Answer 7

NO THEY ARE NEUTRAL