Fuels and Earth Science T8 Flashcards
What is crude oil?
Our main source of hydrocarbons and is used as a raw material to create lots of useful substances used in the petrochemical industry
How is crude oil formed?
It’s formed underground, over millions of years ( at high temperatures and pressures) from the buried remains of plants and animals. It’s a non renewable resource, so 1 day it will run out
What are hydrocarbons?
Compounds that only contain carbon and hydrogen. The hydrocarbons found in crude oil are mostly alkanes (hydrocarbons with the general formula of CnH2n+2)
What are fractions?
Simpler, more useful mixtures containing groups of hydrocarbons of similar lengths. The fractions (eg petrol, kerosene and diesel) are non renewable fossil fuels
What do longer hydrocarbons have in terms of temperature?
A higher boiling point, they turn back into liquids and drain out of the column early on
What is petrol used as?
Petrol is used as fuel in cars
What is kerosene used for?
Kerosene is used as a fuel in aircraft
What is diesel used for?
Diesel is used as a fuel in some cars and larger vehicles e.g trains
What is fuel oil used for?
Fuel oil is used as a fuel for large ships and also in some power stations
What is bitumen used for?
Bitumen is used to surface roads and roofs
What are refinery gases used for?
The gases in this fraction are used in domestic heating and cooking
What is a homologous series?
The homologous series is a family of molecules which have the same general formula and share similar chemical properties
How much does each molecular formula differ from a neighbouring compound?
By CH2
What are 2 different homologous series of hydrocarbons?
Alkanes and alkenes
What does viscosity mean?
Measures how easily a substance flows
Which hydrocarbons are easier to ignite?
Shorter hydrocarbons as they have lower boiling points
Why do the intermolecular forces break easier between smaller molecules than larger molecules?
The forces are much stronger between big molecules than smaller molecules. Thats why big molecules have higher boiling points
What state are longer hydrocarbons at room temperature?
Liquids. They have much higher boiling points and are harder to ignite
Why do hydrocarbons make good fuels?
Because the combustion reactions that happen when you burn them in oxygen give out lots of energy
What is complete combustion?
When you burn hydrocarbons in plenty of oxygen, the only products are carbon dioxide and water
How does incomplete combustion happen?
Incomplete combustion occurs when a hydrocarbon burns in a limited supply of oxygen. It produces carbon monoxide and carbon in the form of soot
How can carbon dioxide be dangerous?
Carbon dioxide can combine with red blood cells and stop your blood from doing its proper job of carrying oxygen around you body, a lack of oxygen can lead to fainting, a coma or even death
How are sulphur dioxide and nitrogen oxide produced?
From burning fossil fuels. The sulfur comes from the impurities in the fossil fuel
How is acid rain formed?
When sulfur dioxide mixes with clouds, it forms dilute sulfuric acid. This falls as acid rain. Acid rain cause lakes to turn acidic and thus killing many animals and plants
What is photochemical smog?
Photochemical smog is a type of air pollution that can cause breathing difficulties, headaches and tiredness
What are the pros of used hydrogen as a fuel?
Hydrogen is very clean, in a hydrogen fuel cell, hydrogen combines with oxygen to produce energy, and the only waste product is water, no nasty pollutants like carbon dioxide
What are the cons of used hydrogen for fuel?
You need a special, expensive engine. Hydrogen gas also needs to be manufactured which is expensive and often uses energy from another source, this energy often comes from burning fossil fuels which produce pollutants
What is cracking?
Cracking turns long saturated (alkane) molecules into smaller unsaturated (alkene) and alkane molecules (which are much more useful)
Why would you crack molecules?
To get more resources which are in higher demand such as diesel and petrol
What can alkene molecules be used for?
Making polymers
In what order does a fractional distillation machine distill substances?
Refinery gases Petrol Kerosene Diesel oil Fuel oil Bitumen
What was the atmosphere of the earth like millions of years ago?
There was no atmosphere
What happened when the earths surface cooled and a thin crust formed?
Volcanos erupted, releasing gases from inside the earth, this degassing released mainly carbon dioxide, but also steam, methane and ammonia.
What happened when the volcanos stopped erupting?
The early atmosphere now only contained mostly CO2 and water vapour
How was nitrogen gas formed in the early atmosphere?
Nitrogen gas was formed by ammonia reacting with oxygen and it was also released by denitrifying bacteria.
Why did the level of nitrogen increase instead of go decrease?
Nitrogen isn’t very reactive so it increased because it was being made and not breaking down
How did the early atmosphere get rid of its carbon dioxide?
Many green plants evolved over most of the earth and removed carbon dioxide and created oxygen
Why is the ozone level (O3) help?
It blocked the harmful rays from the sun
What is the test for oxygen?
You can test for oxygen by checking if the gas will relight a glowj g splint
How do more people mean for the atmosphere?
More people mean more fossil fuels need to be burned for their lighting and heating. More land also needs to be created which leads to deforestation. Deforestation means that the 1 main source for removing oxygen from our atmosphere is slowly being reduced
What does the sun give out?
Electromagnetic radiation
What happens to the electromagnetic radiation as it reaches our atmosphere?
Some electromagnetic radiation passes through our atmosphere. The electromagnetic radiation with short wavelengths are absorbed by the earth, warming the planet
What are greenhouse gases?
Greenhouse gases are the gases in the atmosphere that can absorb and reflect heat radiation. They’re only present in small amounts. Carbon dioxide ,water vapour and methane are 3 green house gases
What happens when there are more green house gases?
More radiation is absorbed by the earth from the sun, warming our planet
Why is methane a problem in recent years?
Because methane is a super effective green house gas and it is produced by farming livestock such as cattle and sheep
What does anthropogenic mean?
It means ‘caused by humans’. Most scientists believe that global warming is anthropogenic
What ways can we see the global levels of carbon dioxide in the past?
Tree rings, fossil and gas bubbles trapped in ice sheets however these method are not very accurate and are less representative of global levels
How could we reduce carbon dioxide emissions?
Instead of driving, we could cycle or turning your central heating down when you leave the house
