C7- organic chemistry

Question 1

What is crude oil?

Answer 1

A mixture of hydrocarbons
Takes thousands of years to form (de composed sea creatures hurried underground)

Question 2

What are alkanes?

Answer 2

Saturated hydrocarbons with a genres, formula of CnH2n+2

Question 3

Describe the combustion of hydrocarbons

Answer 3

Exothermic reaction occurring when hydrocarbons are reacted with oxygen
COMPLETE COMBUSTION:
alkane + oxygen—> carbon dioxide + water
INCOMPLETE COMBUSTION:
alkane + oxygen —> carbon monoxide +water or carbon + water

Question 4

Describe the physical properties of alkanes

Answer 4

First few in series are gases, then liquids, then to solids
In general, boiling points and viscosity increase as molecules get bigger
Volatility and flammability decreases as molecules get bigger
Poor reactivity

Question 5

Explain how fractional distillation of crude oil takes place

Answer 5

1) Crude oil is heated and vaporised
2) Vapor rides up the fractional tower
3) The tower is hotter at the bottom and cooler at top
4) hydrocarbons cool as they go up and condense at different heights, due to different boiling points.
5) Large molecules(high boiling points) collected at bottom
6) Small molecules (low boiling points) collected at top

Question 6

What is cracking?

Answer 6

When large alkanes are thermally broken down in smaller alkanes and alkenes.

Question 7

What are the types of cracking?

Answer 7

-Catalytic- heat alkanes to Vapor and pass them over a hot catalyst
-Steam- heat alkanes to Vapor, mix with steam and heat to a high temperature

Question 8

What is an alkene?

Answer 8

Unsaturated hydrocarbon. (Contains a C=C bond).
GENERAL FORMULA: C(n)H(2n)

Question 9

What is the test for alkenes?

Answer 9

Add bromine water. Colour will change from orange to colourless

Question 10

Describe the combustion of alkenes

Answer 10

Burn with smoky flames due to incomplete combustion