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Flashcards in C8 Deck (21):

What is a hydrocarbon

Any compound formed from carbon and hydrogen atoms only


What is an alkane?
What is the general formula?

Alkanes are the simplest type of hydrocarbon you can get.
They have the general formula CnH2n+1


What is crude oil

Crude oil is a fossil fuel. It's formed from plant and animal remains (plankton)

Non renewable and finite

Mixture of hydrocarbons (mainly alkanes)


What process separates crude oil

Fractional distillation


How does fractional distillation work

Crude oil is heated
Turns to gas
Enters column
Temp gradient causes the hydrocarbons to separate into fractions (longer hydrocarbons=higher boiling point)
Condense back to liquid
Can be collected separately
Each fraction contains a mixture of hydrocarbons with similar numbers of carbon atoms


Recall the different fractions crude oil separates into

B - Bitumen
H - Heavy Fuel Oil
D - Diesel Oil
K - Kerosene
P - Petrol
L - Liquified Petroleum Gas ⛽️

(Big ______ _______ keep _______ polly ______)


Recall the uses for the different fractions

L - heating and cooking
P - cars
K - planes
D - lorries
H - ships and power stations
B - road surfacing


What is a homologous series of hydrocarbon compounds

A group of organic compounds that react in a similar way e.g. alkanes and Alkenes


What is the simplest type of hydrocarbon

What is the general formula




Describe complete combustion of hydrocarbons

Plenty of oxygen...

Hydrocarbon + oxygen ---> carbon dioxide + water + lots of energy



Describe incomplete combustion

Little oxygen in the air... so little oxygen in the products

Carbon monoxide and carbon are also products (as well as CO2 and H2O)

CO - prevents red blood cells from carrying oxygen

C - "soot" reduces air quality / cause of breathing problems


Why is carbon monoxide considered toxic?

Because it binds to the iron in haemoglobin in the blood, preventing it from carrying oxygen


What do impurities in the fossil fuels cause

Sulphur dioxide

Come from sulphur impurities in fossil fuels


Explain the formation of acid rain

Sulphur dioxide mixes with the clouds to form dilutes sulphuric acid

This then falls as acid rain


What are the problems associated with acid rain

It causes lakes to become acidic- death of plants and animals
Kills trees
Corrodes metals
Damages limestone buildings


Explain how nitrogen oxides are formed and how they are pollutants

Nitrogen plus oxygen in the air equals nitrogen oxide

This is a harmful pollutant
It can cause acid rain and photochemical smog (air pollution that causes breathing difficulties headaches and tiredness


What are the pros of using hydrogen as a fuel

Very clean
Hydrogen fuel cell ---> hydrogen + oxygen = water💦 (only waste product)
Hydrogen is obtained from water which is renewable


What are the cons of using hydrogen as a fuel

Needs a special expensive engine
Needs to be manufactured (requires energy, often from fossil feels)
Hard to store


What is cracking and why is it necessary

Cracking is the splitting up of long chains of hydrocarbons to produce smaller, more useful chains

(We need petrol more than we need bitumen)


Recall the gases produced by volcanic activity that formed Earths early atmosphere

Mostly water vapour and carbon dioxide


What were the oceansformed from

When the water vapour later condensed, oceans formed