Lesson 3: Properties of hydrocarbons

Question 1

How does the viscosity of a hydrocarbon change with increasing molecular size (ie. larger hydrcarbon chain?)

Answer 1

• Larger molecular size = increased viscosity.

Question 2

What is meant by “viscosity?”

Answer 2

• Viscosity = how easy/ hard it is to pour a substance.
• Ie. Honey is more viscous than water.

Question 3

How does the boiling point of a hydrocarbon change with increasing molecular size (ie. larger hydrocarbon chain?)

Answer 3

• Larger molecular size = increased boiling point.

Question 4

How does the fammability of a hydrocarbon change with increasing molecular size (ie. larger hydrocarbon chain?)

Answer 4

• Larger molecule size = lower flammibility
• Short- chain hydrocarbons are MORE flammable than long- chain hydrocarbons.

Question 5

What is the equation for the COMPLETE combustion of a hydrocarbon?

Answer 5

hydrocarbon + oxygen —> carbon dioxide.
ENERGY is also released during the combustion of a hydrocarbon.

Question 6

What happens to the elements in the hydrocrabon during the complete combustion of a hydrocarbon?

Answer 6

• The carbon and hydrogen (in the fuels) are oxidised.