Ch9 Crude oils and fuels

Question 1

Crude oil contents

Answer 1

mixture of hydrocarbons with lots of different boiling points

petrol
naphtha
kerosene
diesel oil
heavy fuel oil 
liquefied petroleum gases
bitumen

Question 2

Formation of crude oil

Answer 2

ancient biomass(plankton) buried under mud

layers of rock are laid down on top which creates high pressure, lack of oxygen and high temperature

conditions creates crude oil

Question 3

fractions

Answer 3

different substances with similair boiling points

Question 4

General formula for alkanes

Answer 4

CnH2n+2

Question 5

Order for hydrocarbons

Answer 5

meth-
eth-
prop-
but-
pent-

Question 6

Hydrocarbons

Answer 6

a compound that contains only hydrogen and carbon atoms

Question 7

hydrocarbon properties

Answer 7

short chain long chain
lower bp < higher bp
higher volatility > lower volatility
low runny viscosity < high thick viscosity
high flammability > low flammability

Question 8

saturated hydrocarbons

Answer 8

alkanes

all carbon bonds are single and covalent

Question 9

unsaturated hydrocarbons

Answer 9

alkenes

contains at least one double bond between carbon atoms

Question 10

Fractional distillation of crude oil

Answer 10

Crude oil is heated(vaporised) and fed into the bottom of the fractionating column
Column is kept hot at the bottom and cooler at the top
Gases move up the column, and the hydrocarbons condense when they reach the boiling point
They are then collected off the side in their separate factions

Question 11

Complete combustion of a hydrocarbon

Answer 11

Produces CO2 and H2O
Carbon and hydrogen oxidise completely when they burn in plenty of air
Transfers lots of energy to the surroundings

Question 12

Incomplete combustion of a hydrocarbon

Answer 12

Carbon and Hydrogen don’t oxidise completely because there is not enough oxygen
Produces water and carbon/carbon monoxide

Question 13

Why crack hydrocarbons

Answer 13

heavier fractions from fractional distillation aren’t useful because

1. high boiling point
2. difficult to vaporise
3. don’t burn easily(poor fuels)

Question 14

How to crack a hydrocarbon

Answer 14

1. Place hydrocarbon into a steel vessel(cracker)
2. heated to vaporise the hydrocarbon
3. a. pass over a hot catalyst
   b. mixed with steam and heated to high temperature

Question 15

cracking hydrocarbons

Answer 15

thermal decomposition reactions

creates alkenes and smaller alkanes

Question 16

Positive test for an unsaturated hydrocarbon

Answer 16

Mix hydrocarbon with orange bromine water

It will turn colourless

Question 17

Homologous series

Answer 17

examples are alkanes or alkenes
compounds have similair properties and structures
compounds have same functional group