C1e

Question 1

What are hydrocarbons?

Answer 1

-any compound that contains carbon and hydrogen only

Question 2

What are alkanes?

Answer 2

• saturated compounds (one single convalent bond)
• will not form polymers
• CnH2n+2

Question 3

What are alkenes

Answer 3

• unsaturated compounds (at least one double bond)
• double bonds can open and join onto things , making alkenes more reactive than alkanes
• CNH2n

Question 4

How are double bonds formed?

Answer 4

-two atoms sharing two pairs of electrons instead of one pair

Question 5

How can you test if a hydrocarbon is an alkene?

Answer 5

• react alkene with bromine water
• shake them together and if the bromine water goes from orange to colourless, it is an alkene
• this is an addition reaction
• bromine adds to the alkene with a double bond to make a colourless dibromo solution
• bromine water has decolourised

Question 6

What are the fractions of crude oil?

Answer 6

-LPG (liquefied petroleum gas)
-petrol
-napatha
-kerosene (paraffin)
-diesel
-oil (fuel oil, heating oil, lubricating oil)
-bitumen
each fraction contains a mixture of hydrocarbon with similar boiling points

Question 7

How is crude oil separated into different hydrocarbon fractions?

Answer 7

-factional distillation
1-oil is heated until mostly gas
2-gases enter the bottom of the factional distillation column (has a temperature gradient)
3-bitumen drains off at the bottom as it is a liquid at the hottest bottom (hot)
-the longer the hydrocarbon the higher the boiling point, turn into liquids and drain out of the column earlier on, near the bottom
-the shorter the hydrocarbon the lower the boiling point, liquefy and drain out nearer the top later on, where it is cooler

Question 8

How do hydrocarbon properties change as the size increases?

Answer 8

• boiling point increases
• less flammable
• more viscous (doesn’t flow as easily)
• less volatile

Question 9

What is crude oil?

Answer 9

• formed from fossils of plants and animals and turn to crude oil by high temperature and pressure
• mixture of lots of different hydrocarbons

Question 10

What important types of bonds are in crude oil?

Answer 10

• strong covalent bonds between carbons and hydrogen within each hydrocarbon molecule
• intermolecular forces of attraction between different hydrocarbon molecules

Question 11

Why do the properties of crude oil change?

Answer 11

-the longer the hydrocarbon, the stronger the intermolecular forces, the higher the boiling and melting point