Unit 1b - Oils, Earth And Atmosphere Flashcards
What do long chain hydrocarbons form?
Thick gloopy liquids like tar
What is the process called that turns longer molecules produced from fractional distillation into smaller ones called?
Cracking
An example of a product from cracking being used as a fuel
Petrol for cars or paraffin for jet fuel
What other substances are produced in cracking besides fuels and what is its purpose?
Ethene. Making plastics.
What can you get when you crack disel?
Petrol, paraffin and ethene
What kind of reaction is cracking?
Thermal decomposition
How do you crack a long chain hydrocarbon?
Heat the long chain hydrocarbons to VAPORISE it then the vapour is passed over a POWDERER CATALYST (aluminium oxide) at a temperature of about 400C - 700C and the long chain molecules SPLIT APART on the surface of the specks of catalyst
What does thermal decomposition reaction mean?
Breaking molecules down by heating them up
What is the catalyst used for cracking?
Aluminium oxide
What are most of the products of cracking called?
Alkanes and Alkenes
What is an alternative way to crack the hydrocarbons?
Mix the vapour with steam at a very high temperature
What is the general word equation for cracking a long chain hydrocarbon?
Long-chain hydrocarbon molecule –> shorter alkane molecule + alkene
(Kerosene –> octane + ethene)
What is the general formula for an alkane?
CnH2n+2
What is the general formula for an alkene?
CnH2n
What does cracking mean?
Splitting up long chain hydrocarbons
What kind of bond do alkenes have?
A C=C double bond
A carbon double bond
Why are alkenes known as unsaturated?
Because they can make more bonds as the double bond can open up allowing the two carbon atoms to bond with other atoms
What are the first two alkenes?
Ethene, propene
What is the formula for ethene?
H H
\ /
C=C
/ \
H HWhat is the formula for propene?
H H H
| | /
H-C-C=C
| \
H HWhat is the test for an Alkene?
Adding the substance to bromine water the Alkene will decolourise the bromine water turning it from orange to colourless.
Why does alkenes turn bromine water colourless ?
The double bond has opened up and formed bonds with the bromine
How can ethene produce ethanol ?
It can be hydrated with steam in the presence of a catalyst to make ethanol
Why is reacting ethene with steam to produce ethanol cheap!
Because ethene is fairly cheap and not much of it is wasted
What is the trouble with using ethene to produce ethanol?
Ethene is produced from crude oil which is non renewable that could start running out fairly soon so using ethene to make ethanol will become very expensive in the future
What can ethanol be produced from besides ethene?
Renewable resources by fermentation
What is the raw material used for fermentation called and how is it converted to ethanol?
Sugar and it is converted into ethanol using yeast
What is the word equation for converting sugar into ethanol?
Sugar –> carbon dioxide + ethanol
What are the advantages to producing ethanol using fermentation instead of ethene?
It requires a lower temperature, simpler equipment, renewable, used as a cheap fuel in some countries that don’t have oil reserves for making petrol
Why is sugar a good material to use to make ethanol?
It is grown as a major crop in several parts of the world including many poorer countries
What are the disadvantages to making ethanol from fermentation instead of ethene?
The ethanol produced isn’t very concentrated so if you want to increase its strength it needs to be distilled (as in whisky distilleries), and it needs to be purified
What kind of bonds do Alkanes have?
single carbon bonds
What was used before polythene bags?
String bags
What can alkenes be used to make?
Polymers
What is it called when you join together lots of small alkene molecules to form large molecules?
Polymerisation
What is polymerisation?
Joining together lots of small alkene molecules to form large molecules and these long chain molecules are called polymers
What are small alkene molecules known as?
Monomers
What can may ethene molecules be joined up to form?
Poly(ethene) or polythene
What does a polymers structure look like?
H H H H H H
| | | | | |
-C-C-C-C-C-C-
| | | | | |
H H H H H HWhat is the general name for a polymer?
Poly(whatever the alkene was)
What do you use for polymerisation?
Pressure and a catalyst
What do the physical properties of a polymer depend on?
What it’s made from
What is an example of something stronger than poly(ethene)
Polyamides
What are a polymers physical properties affected by?
Temperature and pressure of polymerisation
What is characteristics of poly(ethene) made at 200*c and 2000 atmospheres pressure
Flexible with a low density
What are the characteristics of poly(ethene) made at 60*c and a few atmospheres pressure with a catalyst
Rigid and dense
What are light, stretchable polymers that are used to make plastic bags called?
Low density poly(ethene)
What are elastic polymer fibres used to make?
Super stretchy Lycra fibre for tights
What are some uses of polymers
Water proof coating force rocks, dental polymers are used in resin tooth filing, polymer hydrogel wound dressings keep wounds moist
What are the new biodegradable packaging materials that are being produced made from?
Polymers and cornstarch
What is an example of a smart material and what is a smart material?
Memory foam And a polymer that gets softer as it gets warmer and mattresses can be made of memory foam
Why are most polymers not biodegradable?
They are unable to be broken down by microorganism so they don’t rots and it’s difficult to get rid of them
What is the best thing to do with polymers that aren’t biodegradable?
Re-use them as many times as possible and recycle then otherwise so they’d be in a land fill site for years
What are things made from polymers in comparison to those made of metal?
Cheaper
Why will the price of crude oil rise and what impact will this have on polymers?
Because crude oil resources get used up so the price of crude oil will rise so will the polymers and one day there el t been ought oil for every use so polymers made using crude oil may not be made
What is an example of naturally occurring polymers?
Rubber and silk
What are some examples of synthetic polymers?
Polyester and PVC
What is an example of a polymer in the body?
DNA
What are examples of foods that contain a lot of oil?
Fruits and seeds e.g avocados, olives, Brazil nuts, peanuts and sesame seeds
What can oils be used for?
Food or fuel
What is the method and its steps to get oil out of fruits and seeds (plants)?
First the plant material is crushed, then press the crushed plant material between metal plates and squash the oil out. Oil can be separated from crushed plant material by a centrifuge (like using a spin dryer to get water out of wet clothes). Or from solvents.
What does distillation do to oils?
It refines them and removes water, solvents and impurities
Why are vegetable oils used in food?
They provide a lot of energy as they have a high energy content, there are other nutrients in vegetable oils e.g vitamin E and they contain essential fatty acids which the body needs for its metabolic processes
Why are vegetable oils good for cooking?
They have a higher boiling point Than water so they can be used to cook foods at a higher temperature and at a faster speed, it gives a different flavour and increases the energy we get from eating the food
Why does cooking with oil give a different flavour?
The oils own flavour but also many flavours come from chemicals that are soluble in water so oil carries the flavour making it more intense however it is more fattening
How can vegetable oil be used to produce fuel?
Vegetables Oils like Rapeseed oil and soybean oil can be processed and turned into fuels because they provide a lot of energy so they are good for fuels
What is biodiesel?
A fuel used from vegetable oils and has similar properties to ordinary diesel fuel as it burns the same way so you can use it to fuel a Diesel engine
What is waste oil from manufacturing and cooking in restaurants useful for?
Being used in pet food and cosmetics
What is the process called to harden oil?
Hydrogenation
What does unsaturated oils contain?
C=C double bonds
What are two properties of oils and fats?
They contain long-chain molecules with lots of carbon atoms and they are either saturated or unsaturated
What will an unsaturated oil do in bromine water and why?
It will decolourise the bromine water because the bromine opens up the double bond and joins on
What do monounsaturated fats contain?
One C=C double bond in Their carbon chains
What do polyunsaturated fats contain?
More than one C=C double bond
What are unsaturated vegetable oils at room temperature?
Liquid
What are the general ways to hydrogenate unsaturated oils?
Reacting them with hydrogen because the hydrogen reacts with the double bonded carbons and opens out the double bond in the presence of a nickel catalyst at about 60*C
What are the differences with hydrogenated oils than unsaturated oils?
Have a higher melting point so they are more solid at room temperature so they are useful for spreads and making cakes and pastures
What is an example of a partially hydrogenated vegetable oil and why was it only partially hydrogenated?
Margarine and because turning all the double bonds in vegetable oil to single bonds would make margarine too hard and difficult to spread so hydrogenating most of them gives margarine a nice, buttery, spreadable consistency.
What are partially hydrogenated vegetable oils often used instead of butter in processed foods and an example?
Biscuits.
Because the oils are must cheaper and butter and they keep longer so they make biscuits cheaper and gives them a long shelf life
What is a disadvantage of partially hydrogenating vegetable oils?
You end up with a lot of so-called trans fats which are suggested to be very bad for you
What are animal fats generally?
Saturated
Why are saturated fats less healthy than unsaturated fats?
Saturated data increase the amount of cholesterol in the blood which can block up arteries and increase the risk of heart disease
What do natural unsaturated fats such as olive oil and sunflower oil do?
Reduce the amount of blood cholesterol
Why are partially hydrogenated vegetable oils bad for your health?
The trans fats in the increase the amount of cholesterol in the blood so eating lots of them can increase the risk of heart disease
What can emulsions be made from?
Lots of little droplets of one liquid suspended in another liquid like oil in water emulsions (oil droplets suspended in water) or water in oil emulsions
What are the physical properties of an emulsion and what does that make the suited for?
Thicker e.g mayonaise is thinker than sunflower oil and vinegar and it makes them suited to lots of uses in food e.g salad dressings and sauces as the emulsion coats things better than plain oil or vinegar
What makes an emulsion so thick?
The amount of oil in an oil-in-water emulsion
Examples of oil-in-water emulsions and percentage of oil?
Milk 3% oil in full fat milk. Single cream 18%. Double cream 50%.
What does adding air to an emulsion do and examples of products?
Whipped cream to give it a fluffy frothy consistency for use as a topping. Ice cream to give it a softer texture so it is easier to scoop out.
What is an example of a non food related emulsion?
Moisturising lotion because the smooth texture of an emulsion makes it easy to rub into the skin
What do some foods contain to help oil and water mix?
Emulsifiers
What are emulsifiers?
Molecules with one part that’s attracted to water and another part that’d attracted to oil or fat.
What is the part in an emulsifier that’s attracted to water called?
Hydrophilic
What is the part in an emulsifier that is attracted to oil called?
Hydrophobic
How do emulsifiers work?
The hydrophilic end of each emulsifier molecule latches onto water molecules where the hydrophobic end attaches to the oil molecule and when you Shake the oil and water and emulsifier together the oil forms droplets surrounded by a coat of emulsifier with the hydrophilic bit facing outwards and other oil droplets are repelled by these hydrophilic bits where the water molecules latch on so they don’t separate out again.
What are the pros of using emulsifiers?
Stops emulsions from separating out
Gives them a longer shelf life
Allows food companies to produce food low in fat but with a good texture
What are the cons of using emulsifiers?
Some people are allergic to certain emulsifiers e.g egg yolk so people have to check the ingredients carefully
What did scientists used to think ‘wrinkles’ in the earths surface was caused by?
The shrinkage of the surface as it cooled down after the earth was formed
Who was the person who has the theory of continental drift?
Alfred Wegener
How did Wegener start investigating his theory of continental drift?
He came across some work listing the fossils of very similar plants and animals which had been found on opposite sides of the Atlantic Ocean and investigated further finding more examples of it.
What did other people who had noticed the similar fossils accept this as?
There has once been land bridges linking the continents so animals has been able to cross but the bridges has sunk or been covered since then
What did Wegener notice besides from the fossils?
Coastlines like that of Africa and South America seemed to match like pieces of a jigsaw so he looked for more evidence and found there were matching layers in hthe e the Coke in different continents, fossils were in the wrong places like tropical plants discovered on arctic islands
When did Wegener feel like he had enough evidence and published his theory of continental drift?
1915
What did Wegener say about the earth in his theory of continental drift?
300 million years ago there was a supercontinent called Pangaea and it broke down into smaller chunks which moved apart and he claimed these chunks - the continents - were slowly drifting apart
Why didn’t many people accept wegeners theory? (3)
His explanation of how the drifting happened wasn’t convincing as he said the continents were ploughing through the sea bed and their movement was caused by tidal forces and the earths rotation, he used inaccurate data in his calculations done made wild predictions of how fast the continents were moving, he wasn’t a proper geologist - he sturdiest astronomy
Why did other scientists say Wegeners theory of continents moving by tidal forces and the earths rotation was impossible?
Because they calculated the forces needed to move the continents like that would have stopped the earth rotating
Why in 1950s were scientists starting to believe wegeners theory?
They were able to investigate the ocean floor and found new evidence (he wasn’t right about everything but his main idea was correct)
What happened by 1960?
Geologists were convinced of continental drift and beouve the earth is made of several chunks called tectonic plates which move about and collide to push land up to create mountains
What are the layers of the earth and their relative sizes?
Crust (very thin between 5k and 50k), the mantle (a lot thicker), core (made of iron and nickel)
What is the shape of the earth?
Almost spherical
What is the crust surrounded by?
The atmosphere
Explain the mantle
It has all the properties of a solid but it can flow very slowly.
Where do radioactive decay take place and what happens?
Within the mantle, it produces a lot of head which causes the mantle to flow In convection currents
What is the core made of?
Iron and nickel
What is the earths surface made up of?
Tectonic plates
What are the tectonic plates?
The crust and the upper part of the mantle are cracking into a number of large pieces and this is what they are called
Why don’t tectonic plates stay in one place?
Convection currents in the mantle cause the plates to drift
How far do most of the tectonic plates move each year?
A few cm
Why do earthquakes occur?
When the tectonic plates move very suddenly
Where do volcanoes and earthquakes often occur?
At the boundary between two tectonic plates
Why is it impossible to predict when tectonic plates will move?
Because they can stay more or less put for a while and then suddenly lurch forward
What are scientists looking at to see if there are any clues when earthquakes might happen?
Things like strain in under grounds rocks but even then it’s only able to say if they are likely not exactly
What are the clues that help to decide if a volcanic eruption might happen soon?
Before an eruption molten rock rises up into chambers near the surface causing the ground surface to bulge slightly this causes mini earthquakes near the volcano but sometimes molten rock cools down instead of erupting so mini earthquakes can be a false alarm.
What are the percentage and elements in the atmosphere?
78% nitrogen, 21% oxygen and small amounts of other gases like carbon dioxide, noble gases and water vapour
What was the first phase of the earth and its atmosphere?
The surface was originally molten so an atmosphere just boiled away. But things cooled down a bit and a thin crust formed but volcanoes continued erupting. The volcanoes gave out lots of gas and that’s how oceans and atmosphere were first formed. The atmosphere was probably mostly carbon dioxide and virtually no oxygen, but will water vapour and small amounts of methane and ammonia and when the water vapour condensed oceans formed.
What elements were in the very early stages of the atmosphere?
A lot of Carbon dioxide , no oxygen, water vapour, methane and ammonia
What was the very early stages of the earths atmosphere a lot like?
The atmosphere of Mars and Venus today
What was phase two of the earth and its atmosphere?
Green plants and algae evolved over most of the earth. A lot of the carbon dioxide dissolved into ocean and the green plants absorbed carbon dioxide and produced oxygen by photosynthesis. They died and were buried under layers of sediment along with the skeletons and shells of marine organisms and the carbon and hydrocarbons inside them became locked up in sedimentary rocks as insoluble carbonates and fossil fuels.
What happened to the carbon and hydrocarbon inside dead plants and skeletons of marine animals?
It became locked up in sedimentary rock as insoluble carbonates like limestone and fossil fuels
What is phase three of the earth and its atmosphere?
The build up of oxygen killed off early organisms that couldn’t tolerate it but allowed other more complex organisms to evolve and flourish. The oxygen created the ozone layer which blocked harmful rays from the sun and enabled more complex organisms to evolve and there is virtually no carbon dioxide left.
How have we learnt a lot about the past atmosphere and explain the process?
From Antarctic ice cores. Each year a layer of ice forms and bubbles of air get trapped inside then it’s buried by the next layer so the deeper the ice the older the air and if you examine the bubbles you can see how the air has changed
What is the primordial soup theory on how life formed?
- Billions of years ago the earths atmosphere was rich in nitrogen, hydrogen, ammonia and methane
- Lightening struck causing a chemical reaction between the gases resulting in the formation of amino acids
- The acids collected in a ‘primordial soup’ - a body of water out of which life gradually crawled out
- The acids gradually combined to produce organic matter which evolved into living organism
What did Miller and Urey do to try and prove the primordial soup theory?
They sealed the gases in their apparatus, heated them, and applied an electrical charge for a week
What did Miller and Urey find from their experiment and what does this suggest?
That amino acids were made but not as many as there are on earth so the theory could be along the right lines but isn’t quite right
What is the ultimate source of minerals and resources?
The earths crust, oceans and atmosphere
What do you do to air to get a variety of products like nitrogen and oxygen?
Fractionally distill it
What are the steps to fractionally distill air?
- Air is filtered to remove dust
- It’s then cooled to -200*c to a liquid
- When cooled water vapour condenses and is removed
- Carbon dioxide freezes and is removed
- The liquified air then enters the fractionating column and is heated slowly
- Remaining gases are separated by fractional distillation but oxygen and argon come out together so another column is used to separate them
What does increasing carbon dioxide levels affect?
The climate and the ocean
What does burning fossil fuels do?
Releases carbon dioxide
What does the increase in carbon dioxide cause?
Global warming which is a type of climate change
Why does the increase in carbon dioxide levels mean a bad thing for the ocean?
They naturally store carbon dioxide as they absorb it for mother atmosphere but the extra carbon dioxide is too acidic which is bad for coral and shellfish and in the future they won’t be able to absorb any more carbon dioxide
