A4. Properties of fractions

4. Describe the trend in physical properties and main uses of the main fractions (focus on boiling point and viscosity)


Small molecules (i.e. Petroleum to Kerosene)

• Low boiling point
• Light in colour
• Easy to light and burn well (Flammable)
• Runny

Large molecules (i.e. Diesel to Bitumen)

• High boiling point
• Dark in colour
• Hard to burn/light (reasonably inflammable)
• Viscous or thick (Bitumen is a solid at room temperature)

Basically, the longer the molecule, the higher the boiling point, the darker the colour, the viscosity increases and they become increasingly harder to set alight.