Chapter 9

Question 1

What is crude oil?

Answer 1

a naturally occurring product, that is made up of long chain molecules made up of hydrogen and carbon only

Question 2

What is the long chain of molecules called?

Answer 2

a hydrocarbon

Question 3

What are the first 4 alkenes?

Answer 3

1 - methane
2 - ethane
3 - propane
4 - butane

Question 4

What is the general formula for alkanes?

Answer 4

CnH2n+2

Question 5

For the hydrocarbon ethane how many carbons and hydrogens does it have?

Answer 5

carbons = 2
hydrogens = 6

Question 6

How can the long chain molecules be separated?

Answer 6

by fractional distillation

Question 7

What is the method for separating the molecules using fractional distillation?

Answer 7

1 - crude oil mixture enters a small column and is heated to a high temp so most molecules are vaporised.
2 - the column is cooler at the top than the bottom, as the gaseous molecules rise up the column they condense until they reach their boiling points.
3 - they are then collected and removed.

Question 8

What are the separate samples called?

Answer 8

fractions

Question 9

In fractional distillation what is the temperature at the bottom and the top?

Answer 9

top = 25*c
bottom = 350*c

Question 10

What are the names for all 7 fractions and what are they used for?

Answer 10

1 - refinery gas = bottled gas
2 - gasoline(fuel) = fuel for cars
3 - naphtha = making chemicals
4 - kerosene = aircraft fuel
5 - diesel oil = fuel for cars, lorries, busses
6 - fuel oil = fuel for ships, power stations
7 - residue = bitumen for roads and roofs

Question 11

As you go up the column what do the hydrocarbons have?

Answer 11

• lower boiling points
• lower viscosity (flow easier)
• higher flammability (ignite easier)

Question 12

What is it called when the chains re broken into 2 small chains?

Answer 12

cracking

Question 13

What are the 2 ways of cracking hydrocarbons? How is it done?

Answer 13

1 - CATALYTIC CRACKING =
* the alkane is brought into contact with a powered aluminium oxide catalyst at moderate pressure and a temperature of around 500*c

2 - STEAM CRACKING =
* the hydrocarbon is mixed with steam and heated to a very high temperature (approximately 850*c)

Question 14

What does the cracking process result in?

Answer 14

two products called = *alkane + *alkene

Question 15

What is the general formula for alkenes?

Answer 15

CnH2n

Question 16

How many carbons and hydrogens are in ethene and what is the binds like?

Answer 16

carbons = 2
hydrogens = 4
bond = a double bond