Oils, Earth and Atmosphere

Question 1

What type of reaction is cracking?

Answer 1

A thermal decomposition reaction

Question 2

Describe the process of cracking.

Answer 2

the long-chain hydrocarbon is heated so it turns into vapour. The vaporised hydrocarbon is then passed over a powdered catalyst at very high temperatures.
The long chain hydrocarbon will ‘crack’ on the surface of the catalyst.

Question 3

What are the products of cracking ?

Answer 3

Alkanes and Alkenes

Question 4

Give the chemical formula of an ALKANE?

Answer 4

CnH2n+2

Question 5

What makes an alkene different from alkane?

Answer 5

Alkenes have double bonds between two of the carbon atoms in their chain.
Alkenes are unsaturated because they can make more bonds by opening up their double bond which allows them to join with other atoms.

Question 6

What is the general formula for an alkene?

Answer 6

CnH2n

Question 7

How can we test for an alkene in a substance?

Answer 7

By adding the alkene in a substance called Bromine water. The water will turn from orange to colourless if an alkene is present, this is because the double bond has opened up and formed bonds with the bromine.

Question 8

Ethene is a product of cracking, what can ethene be used to make?

Answer 8

Ethanol

Question 9

Describe the process of making Ethanol with Ethene.

Answer 9

Ethene is hydrated with steam in the presence of a catalyst to make Ethanol.

Question 10

Give the pro’s and Cons of making Ethanol this way.

Answer 10

PRO’S
Cheap process (at the moment)
Ethene is fairly cheap
Not much wasted

CONS
Ethene is produced from crude oil which is non-renewable, it could start running out so using ethene to make ethanol will become very expensive.

Question 11

What other way can we make Ethanol?

Answer 11

Fermentation

Question 12

Describe how you would make Ethanol using the fermentation process.

Answer 12

Sugar from plants is converted into Ethanol using yeast. Enzymes in the yeast act as a natural catalyst to make this process happen. Another product formed is carbon dioxide.

Question 13

Give the pro’s and con’s of fermentation.

Answer 13

PRO'S 
lower temperature 
simpler equipment then Ethene.
renewable source, uses a raw material.
can be used as a cheap fuel.
CON'S 
Ethanol produced is not very concentrated, if you wanted to increase its strength you have to distil it.
Needs to be purified.
If sugar plants are being grown for fuel, there is less being grown for food so food prices will rise.

Question 14

What is polymerisation?

Answer 14

Polymerisation means joining together lots of small alkene molecules to form very large molecules.

Question 15

How do we extract oils from plants?

Answer 15

The plant material is crushed.
Then the crushed plant is pressed between metal plates which squashes the oil out.
The oil is then refined using distillation which removes water, solvents and impurities.

Question 16

What are vegetable oils used for?

Answer 16

Food- healthy
Cooking- speed up cooking, oil has a higher boiling point then water so food can be cooked at a higher temperature faster.
Also gives a different flavour
Increases the energy we get from it.
To produce fuels- biodiesal

Question 17

What are mono unsaturated fats?

Answer 17

fats that contain only one carbon double bond in their long-chain molecule.

Question 18

what are polyunsaturated fats?

Answer 18

Fats containing more than one carbon double bond.

Question 19

How can we harden unsaturated vegetable oils?

Answer 19

By reacting them with hydrogen in the presence of a nickel catalyst at 60 degrees. We call this hydrogenation.
The hydrogen reacts with the doubled-bonded carbons and opens out the double bond.

Question 20

How is margarine made?

Answer 20

It is made from partially hydrogenated vegetable oil, this gives it a nice buttery, spreadable consistency as completely hydrogenating it would make it too hard.

Question 21

Why are partially hydrogenated vegetable oils used instead of butter?

Answer 21

Cheaper, keep longer.

Question 22

What is the down side to partially hydrogenated vegetable oils?

Answer 22

They contain trans-fats. Trans-fats increase the amount of cholesterol in the blood.

Question 23

What are emulsions made up of?

Answer 23

Lots of droplets of one liquid suspended in another liquid. E.G. an oil in water emulsion. Emulsions make a substance thicker.

Question 24

How do emulsifies help oil and water mix?

Answer 24

Oils and water naturally separate out. Emulsifiers have a hydrophilic head which laches onto the water molecules and a hydrophobic tail which is attracted to the oil and suspends itself into the oil molecule. This prevents the oil and water from separating.

Question 25

Good and bad sides to emulsifiers.

Answer 25

gives mixtures longer shelf life.
allow food companies to produce food that’s lower in fat but that still have a good texture.

Some people are allergic to emulsifiers.

Question 26

Who was Alfred Wegener and what did he discover?

Answer 26

Wegener was a scientist who came up with the theory of continental drift. He noticed that the modern continents looked like they could fit together, like they were once together and then had split apart.

Question 27

Why wasn’t Wegner’s theory accepted for many years?

Answer 27

He couldn’t explain how the continents drifted apart, he had used inaccurate data in his calculations.

Question 28

How are mountains formed?

Answer 28

collision between two tectonic plates pushes the land up to form a mountain.

Question 29

Name the layers of the earth, starting with the layer we live on.

Answer 29

Crust, mantle, outer core, inner core.

Question 30

What are tectonic plate?

Answer 30

Large segments of the crust and upper part of the mantle which are cracked.

Question 31

How do tectonic plates drift apart?

Answer 31

radioactive decay in the mantle produces lots of heat. This produces a convection current which causes the tectonic plates on the crust to slowly drift apart.

Question 32

What gases did the early atmosphere consist of and how were they formed?

Answer 32

Carbon dioxide and small amounts of methane and ammonia , with water vapour. This was given out by volcanoes.

Question 33

How did the oceans form?

Answer 33

When the water vapour condensed it formed the oceans.

Question 34

How did the evolution of plants and algae change the atmosphere?

Answer 34

The green plants and algae absorbed the carbon dioxide from the atmosphere and produced oxygen by photosynthesis. The CO2 in the early atmosphere was dissolved into the ocean.

Question 35

What is ‘locked-up’ carbon?

Answer 35

carbon dioxide in plants and algae that have been buried under rocks for thousands of years.

Question 36

Explain the primordial soup theory.

Answer 36

The earth early atmosphere was rich in nitrogen, hydrogen, ammonia and methane. Lightning struck and caused a chemical reaction between the gases resulting in the formation of amino acids. The amino acids collected in a primordial soup and eventually combined to form organic matter which evolved into simple living organisms.

Question 37

Who carried out an experiment to prove this theory?

Answer 37

Miller and Urey