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Chemistry 1 > C1 Part B > Flashcards

C1 Part B Flashcards

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1
Q

What is cracking?

A

The splitting up of long chain hydrocarbons.

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2
Q

List three products of cracking and their uses

A
  • Petrol to fuel cars
  • Paraffin for jet fuel
  • Ethene for making plastic
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3
Q

What kind of reaction is cracking?

A

Thermal decomposition

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4
Q

Describe the three main steps of cracking

A
  1. The long-chain hydrocarbon is heated and vaporised.
  2. The gas is then passed over a powdered catalyst (aluminium oxide) at a temperature of 400 - 700 degrees
  3. The long chain molecules will split apart on the surface of the powdered catalyst
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5
Q

What are the products when kerosene (10 carbon atoms) is “cracked”?

A

Octane (an alkane with eight carbon atoms) and Ethene (an alkene with two carbon atoms)

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6
Q

Can you give an alternative method of splitting up long chain hydrocarbons?

A

The vapour is mixed with steam at a very high temperature.

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7
Q

What are alkenes?

A

Hydrocarbons that have a double bond between two of the carbon atoms in their chain

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8
Q

Why are alkenes known as “unsaturated”?

A

They can make more bonds by the double bond between two carbon atoms opening up.

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9
Q

What is the general formula for alkenes?

A

CnH2n

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10
Q

How can you test for an alkene?

A

By adding a substance to bromine water, if the water goes from orange to colourless it means that an alkene is present. The colour change happens because the double bond has opened and formed bonds with the bromine.

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11
Q

How is ethanol produced from ethene and why is this a problem?

A

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

Ethene is a product from crude oil, it will eventually become more expensive to make ethanol as crude oil is a non-renewable resource.

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12
Q

What is the process by which ethanol can be produced from renewable resources? Give the word equation

A

Ethanol is the alcohol in beer and wine, in these products it is created by fermentation. Sugar is converted into ethanol using yeast.

Sugar → Carbon Dioxide + Ethanol

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13
Q

What are the pros (4) and cons (2) of creating ethanol from the fermentation of sugar?

A

Pros:

  • Needs a lower temperature and simpler equipment than when using ethene
  • Sugar is a renewable resource
  • Sugar crops are largely grown in poorer areas of the world
  • Can be used as a cheap fuel

Cons:

  • The ethanol produced isn’t very concentrated so it must be distilled to increase it’s strength
  • The ethanol produced needs to be purified
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14
Q

Define polymerisation

A

Joining together lots of small alkene molecules (monomers) to form very large molecules called polymers

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15
Q

Name the polymers of ethene and propene

A

Polyethene (or polythene)

Polypropene

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16
Q

What do the physical properties of polymers depend on? (3)

A
  • What its made from eg. polyamides are stonger than polythene
  • The temperature of polymerisation
  • The pressure of polymerisation
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17
Q

What is the difference between polythene made at 200 degrees and that made at 60 degrees with a catalyst?

A
  • Made at 200 degrees and 2000 atmospheres: flexible and has a low density
  • Made at 60 degrees and a few atmospheres pressure with a catalyst: rigid and dense
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18
Q

Name as many uses of polymers as you can (7)

A
  • Elastic polymer fibres are used to make stretchy lycra fibre for tights
  • Light stretchable polymers (such as low density ethene) are used to make plastic bags
  • Waterproof coating for fabric
  • Resin in tooth fillings
  • Hydrogel wound dressings
  • Biodegradable packaging
  • Memory foam
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19
Q

What disadvantages are there to the wide use of polymers? (2)

A
  • They’re not biodegradable
  • The alkene products their made of come from products of crude oil, a non-renewable resource
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20
Q

How are oils extracted from plants and seeds? (3 different methods) What is distillation?

A
  • The plant material is crushed and then pressed between metal plates, causing the oil to seep out.
  • Centrifuge
  • Solvents can be used to get oil from plant material.

Distillation refines oil, removing water, solvents and impurities.

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21
Q

What are the benefits of using vegetable oils in food? (3)

A
  • High energy content
  • Vitamins eg. seeds contain Vitamin E
  • Contain essential fatty acids that the body need to metabolic processed.
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22
Q

Why are vegetable oils used in cooking?

A
  • Higher boiling points than water
  • Intensify flavour (chemicals are soluble in the oil)
  • Increases the energy we get from eating the food
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23
Q

What is another use of vegetable oils, other than consumption?

A

Can be processed to make biofuels like biodiesel - can be used in a normal diesel engine.

24
Q

What are the molecules in oils and fats like?

A

They are long-chain molecules with lots of carbon atoms, either saturated or unsaturated.

25
Q

Unsaturated oils contain what type of bonds between some of their carbon atoms? And what does an unsaturated oil do to bromine water?

A

Double bonds

Unsaturated oils will decolourise bromine water.

26
Q

What’s the difference between monounsaturated fats and polyunsaturated fats?

A

Monounsaturated fats contain one C=C double bond in their carbon chains wherease polyunsaturated have more than one.

27
Q

How can unsaturated oils be hardened?

A

They are reacted with hydrogen in the presence of a nickel catalyst at 60 degrees. The hydrogen reacts with the double bonded carbons and opens them out. This is known as hydrogenation.

28
Q

What is margarine made from?

A

Partially hydrogenated vegetable oils

29
Q

Why are partially hydrogenated vegetable oils widely used in processed foods and why does this cause concern?

A

The oils are a lot cheaper than butter and they keep longer.

Partially hydrogenated vegetable oils means you end up with a lot of trans-fats and there’s evidence to suggest these trans fats are very bad for health.

30
Q

Which type of fats tend to be saturated?

A

Animal

31
Q

Why do saturated fats and partially hydrogenated fats tend to be less healthy than unsaturated?

A

They increase the amount of cholesterol in blood, this can block arteries and cause heart disease.

32
Q

How are emulsions made?

A

Droplets of one liquid are suspended in another liquid eg. oil-in-water or water-in-oil emulsions

33
Q

What is the difference between oil/water and emulsions? Give an example of an emulsion and the components that make it

A

Emulsions are thicker than both oil and water eg. Mayonnaise is thicker than sunflower oil and vinegar

34
Q

What is the general rule of the amount of oil in an oil-in-water emulsion and its thickness?

A

The more oil in an emulsion, the thicker it is

35
Q

What is the extra ingredient to the oil-in-water emulsions whipped cream and ice cream, why is it included?

A

Air is whipped into cream in order togive it a fluffier consistency and softer texture

36
Q

Give one non-food use of emulsion

A

Moisturising lotions

37
Q

Define the term ‘emulsifier’

A

Emulsifiers are molecules with one part that is attracted to water and another that’s attracted to oil or fat

38
Q

What’s is the difference between the hydrophilic part of an emulsifier molecule and the hydrophobic part?

A

Hydrophilic: Attracted to water

Hydrophobic: Attracted to oil

39
Q

What happens to the molecules when you shake oil and water together with an emulsifier?

A

The oil forms droplets surrounded by a coating of the emulsifier, with the hydrophilic part facing outwars so that water molecules can latch on and the emulsion won’t seperate.

40
Q

What are the pros (2) and cons (1) of using emulsifiers?

A

Pros:

  • Stops emulsions from separating and gives them a longer shelf life
  • Allows food companies to produce food thats lower in fat

Cons:

  • Some people are allergic to emulsifiers eg. egg yolk
41
Q

What does Alfred Wegener’s theory published in 1915 desribe?

A

The process of continental drift. Wegener said that about 300 million years ago, there has been just one large continent (known as Pangaea) that broke into smaller pieces, which moved apart from one another. He said these chunks, our modern-day continents contine to driftt apart.

42
Q

Why wasn’t Wegener’s theory accepted for many years? (4)

A
  • He said the continents were effectively ploughing through the sea bed and this movement was caused by tidal forces and the earth’s rotation
  • One scientist calculated that the forces necessary to move the continents would also have stopped the Earth’s rotation
  • Wegener used some inaccurate data, which caused him to make some wld predictions about the rate of continental drift.
  • He wasn’t deemed a ‘proper’ geologist because he’d studied astronomy
43
Q

What theory, formulated in the 1950s, went some way to proving that Wegener was quite right about continental drift?

A

Plate tectonics

44
Q

Can you describe the structure of the Earth? Use a diagram if it helps

A
45
Q

How thick is the crust of the earth?

A

Between 5-50km

46
Q

What happens in the mantle?

A

Radioactive decay occurs, producing a lot of heat and causing the mantle to flow in convection currents.

47
Q

What two metals do scientists believe the core of the earth is made of?

A

Iron and Nickel

48
Q

What causes tectonic plates to move and how fast do they travel?

A
  • Convection currents
  • A few centimeters per year
49
Q

Why is it difficult for scientists to predict natural disasters (such as earthquakes and volcanic eruptions) that are caused by the movement of tectonic plates?

A
  • Tectonic plates can move sporadically and suddenly lurch into another position
  • Before a volcanic eruption, molten rock rises into chambers and can often cause the earth to bulge slightly and mini-earthquakes to occur. Sometimes this rock will cool down instead of actually erupting.
50
Q

Describe the composition of the Earth’s atmosphere

A

78% Nitrogen

21% Oxygen

  1. 9% Argon
  2. 037% CO2
51
Q

What happened during phase 1 of the evolution of the atmosphere? What planets in the present day is this comparable to?

A

The Earth’s surface was molten and thus any atmosphere would boil away into space. When it began to cool, a crust formed but volcanoes continued to erupt and give out gas. It is believed the early atmosphere was mainly CO2, with small amounts of water vapour, methane and ammonia. Oceans formed when the water capour condensed.

Very like Mars and Venus.

52
Q
A
53
Q

Describe phase 2 of the evolution of the atmosphere. Link this back to topics discussed earlier in C1.

A

Green plants and algae evolved, absorbing CO2and emitting oxygen by photosynthesis. When plants and algae died they were buried under sediment and the carbon/hydrocarbons in them became lockes in sedimentary rocks (limestone) and fossil fuels

54
Q

What is the atmosphere like now we are in phase 3 of its evolution?

A

The build up of oxygen killed off some early organisms and formed an ozone layer (O3) which blocks harmful rays from the Sun and allowed more complex organisms (like us) to develop.

55
Q

Outline the primordial soup theory’s description of how life was formed on Earth

A
  • Billions of years ago, lighting struck and caused a reaction betwen gases in the Earth’s atmosphere, resulting in the formation of amino acids.
  • The amino acids combined to produce organic matter and eventually living organisms
56
Q

How did Miller and Urey test the primordial soup theory and what was their conclusion?

A

They sealed gases and apparatus heated them and applied an electrical charge for a week.

They found amino acids were created but not as many as there are on Earth.

57
Q

How can we fractionally distil air to get a variety of products? (5 main steps)

A
  • Air is filtered to remove dust
  • It is cooled to -200 degreed
  • Water vapour condenses and is removed
  • Carbon dioxide freezes and is removed
  • Liquified air is then heated slowly and the remaining gases are separated (oxygen and argon come out together so another column is used for them)

Chemistry 1 (2 decks)

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