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(GCSE) Chemistry > C9. Crude Oil And Fuels (Y11 - Spring 1) > Flashcards

C9. Crude Oil And Fuels (Y11 - Spring 1) Flashcards

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1
Q

🟢 What are Hydrocarbons

A

A hydrocarbon is any compound that is formed from carbon and hydrogen atoms only.

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2
Q

🟢 What are Alkanes (+their formula, the series they’re in, their compounds)

A

(Alkanes all have C-C single bonds)

  1. Alkanes are the simplest type of hydrocarbon you can get. They have the general formula CnH2n+2.
  2. The alkanes are a homologous series - a group of organic compounds that react in a similar way.
  3. Alkanes are saturated compounds - each carbon atom forms four single covalent bonds
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3
Q

🟢 What are the first 4 Alkanes

A

The first four alkanes are methane, ethane, propane, and butane.

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4
Q

🟢 Hydorcarbon Properties as they get Smaller

A
  1. The shorter the carbon chain, the more runny a hydrocarbon is - that is, the les viscous it is.
  2. Hydrocarbons with shorter carbon chains are also more volatile, i.e they have lower boiling points
  3. Also, the shorter the carbon chain, the more flammable the hydrocarbon is
  4. The properties of hydrocarbons affect how they’re used for fuels. E.g short chain hydrocarbons with lower boiling points are used as ‘bottled gases’ - stored under pressure as liquids in bottles
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5
Q

🟢 What happens in the Complete Combustion of any Hydrocarbon in Oxygen

A
  1. The complete combustion of any hydrocarbon in oxygen releases lots of energy. This only waste products are carbon and water vapour
    * Hydrocarbon + Oxygen —> Carbon Dioxide + Water*
  2. During combustion, both carbon and hydrogen from the hydrocarbon are oxidised
  3. Hydrocarbons are used as fuels due to the amount of energy released when they combust completely.
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6
Q

🟢 What is Crude Oil

A

Crude oil is a mixture of hydrocarbons that exists in a liquid phase in natural, underground reservoirs. Crude oil is a fossil fuel. It’s formed from the remains of plants and animals, mainly plankton

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7
Q

🟢 How is Crude Oil Separated

A

It’s separated through a process called Fractional Distillation

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8
Q

🟢 What Happens in Fractional Distillation (Process of Fractional Distillation)

A
  1. The oil is heated until most of it has turned into gas. The gases enter a fractional distillation column (and the liquid bit is drained off).
  2. In the column, there’s a temperature gradient (it’s hot at the bottom and gets cooler as you go up).
  3. The longer hydrocarbons have high boiling points. They condense back into liquids and drain out of the column early on, when they’re near the botton. The shorter hydrocarbons have lower boiling points. (The hydrocarbons cool and condense as they go up). They condense and drain out much later on, near to the top of the column where it’s cooler.
  4. You end up with the crude oil mixture separated out into different fractions. Each fraction contains a mixture of hydrocarbons that all contain a similar number of carbon atoms, so have similar boiling points.
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9
Q

🟢 What various important uses does Crude Oil have in modern life

A
  1. Oil provides the fuel for most modern transport - cars, trains, planes, the lot. Diesel oil, kerosene, heavy fuel, and LPG (liquid petroleum gas) all come from crude oil
  2. Th petrochemical industry uses some of the hydrocarbons from crude oil as a feedstock to make new compounds for use in things like polymers, solvents, lubricants, and detergents
  3. All the products you get from crude oil are examples of organic compounds (compounds containing carbon atoms). The reason you get such a large variety of products is because carbon atoms can bond together to form different groups called homologous series. These groups contain similar compounds with many properties in common. Alkanes and alkenes are examples of different homologous series.
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10
Q

🟢 Are the fractions pure substances or mixtures? How can you tell?

A

The fractions are all mixtures, as there are temperature ranges in different fractions, and pure substances melt and boil at specific temperatures

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11
Q

🟢 The hydrocarbons in crude oil have different properties. Which of these properties does separation by fractional distillation depend on?

A

The properties that separation by fractional distillation rely on is the mass of the hydrocarbons.

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12
Q

🟢 What out of Decane and Pentane has:

  • Higher Boiling Point
  • Is More Runny
  • Catches Fire Easily
  • Burns With Smokier Flame
  • Collects Higher Up The Fractionating Column

(Decane: C10H22, Pentane: C5H12)

A

Higher Boiling Point:
Decane

Is More Runny:
Pentane

Catches Fire Easily:
Pentane

Burns With Smokier Flame:
Decane

Collects Higher Up The Fractionating Column:
Pentane

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13
Q

🟢 Kerosene is a fraction of crude oil used as fuel for aeroplanes. Is kerosene a pure substance or a mixture?

A

Kerosene is a mixture, because it is a fraction, and a fraction boils over a range of temperatures rather than a specific temperature, meaning it’s a mixture of all hydrocarbons between C11-C15.

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14
Q

🟢 Saturated Hydrocarbon Definition

A

A saturated hydrocarbon will only have single bonds, as it has the maximum amount of hydrogen molecules.

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15
Q

🟢 Unsaturated Hydrocarbon Definition

A

An unsaturated hydrocarbon will contain one or more double bonds.

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16
Q

🟢 Homologous Series Definition

A

Is a group of compounds with the same general formula, the same functional group, and therefore similar chemical properties.

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17
Q

🟢 What are Alkanes?

A

Alkanes are a homologous series of hydrocarbons with the general formula CnH2n+2

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18
Q

🟢 Give the molecular formula of an alkane containing 6 carbon atoms

A

C6H14

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19
Q

🟢 Give the molecular formula of an alkane containing 9 carbon atoms

A

C9H20

20
Q

🟢 Write balanced equation(s) for the complete combustion of propane (C3H8)

A

C3H8(g)+5O2(g)→3CO2(g)+4H2O(g)

21
Q

🟢 Write balanced equation(s) for the complete combustion of ethane (C2H6)

A

C2H6+5O2→2CO2+3H2O+ Heat

22
Q

🟢 Write balanced equation(s) for the incomplete combustion of ethane (C2H6)

A

2C2H6 + SO2 —> 4CO + 6H2O

23
Q

🟢 Why is the complete combustion of a hydrocarbon an oxidisation reaction

A

The carbon and hydrogen in the fuel are oxidised completely when they burn like this. Remember that one definition of oxidisation means adding oxygen in a chemical reaction.

24
Q

🟢 What are the products of complete combustion of a hydrocarbon

A

The products of complete combustion of a hydrocarbon are carbon dioxide and water

25
Q

🟢 How can you test for water formed in the complete combustion of a hydrocarbon

A

As well as using blue cobalt chloride paper to test for the water formed in the complete combusion of a hydrocarbon, you can also use white anhydrous copper sulphate. On contact with water, the white powder turns blue.

26
Q

🟢 What is Incomplete Combustion and how does it happen

A

All fossil fuels - oil, coals, and natural gas - produce carbon dioxide and water when they burn in plenty of air. However, when there is not enough oxygen, for example, inside an engine, there is incomplete combustion.

Instead of all of the carbon in fuel turning into carbon dioxide, carbon monoxide gas, CO, is also formed. Carbon monoxide is a toxic gas. It is colourless and odourless. Your red blood cells pick up this gas and carry it around in your blood instead of oxygen.

27
Q

🟢 What is the General formula for an Alkane

A

CnH2n+2

28
Q

🟢 Molecular Formula for:

  • Methane
  • Ethane
  • Propane
  • Butane
A

Methane:
CH4

Ethane:
C2H6

Propane:
C3H8

Butane:
C4H10

29
Q

🟢 What type of series are the Alkanes in and what is the difference between each alkane

A

The alkanes are a homologous series, meaning they have the same general formula, same functional groups, and each one in the series differs to the next by CH2.

30
Q

🟢 Why are all the Alkanes saturated hydrocarbons

A

They are all saturated hydrocarbons, because they are compounds of hydrogen and carbon only, and they are all single covalent bonds.

31
Q

🟢 When does Complete Combustion happen with a hydrocarbon and what type of reaction is it

A

Complete combustion is when a hydrocarbon burns in the maximum amount of oxygen to form water and carbon dioxide. It is an oxidation reaction because the hydrocarbon gains oxygen and it is also an Exothermic reaction, as energy is released to the surroundings during the reaction.

32
Q

🟢 Construct Balanced Chemical Equations for the Complete Combustions of the first 4 Alkanes (Include State Symbols)

A

Methane:
CH4 (g) + 3O2 (g) —> CO2 (g) + 2H2O (g)

Ethane:
2C2H6 (g) + 7O2 (g) —> 4CO2 (g) + 6H2O (g)

Propane:
C3H8 (g) + O2 (g) —> 3CO2 (g) + 4H2O

Butane:
2C4H10 (g) + 13O2 (g) —> 8CO2 (g) + 10H2O (g)

33
Q

🟢 A cylinder of propane contains 16.00kg of liquefied gas. Using the balanced chemical equation calculate the minimum mass of oxygen needed for complete combustion of the gas in the cylinder.

A

C3H8 (g) + O2 (g) —> 3CO2 (g) + 4H2O (g)

16000g/44 = 363.63

  1. 63 x 5 = 1818.18
  2. 18 x 32 = 58181.81g

= 58.181kg

34
Q

🟢 Why should we crack Hydrocarbons

A

Some of the heavier fractions from the fractional distillation of crude oil are not in high demand. The hydrocarbons in them are made up of large molecules. They are thick liquids or solids with high boiling points. They are difficult to vaporise and do not burn easily - so they are poor fuels. Yet the main demand from crude oil is for fuels and starting materials (feedstock) for the chemical industry. Fortunately, the larger, less useful hydrocarbin moleucles can be broken down into smaller, more useful ones in a process we can cracking.

35
Q

🟢 How do we crack Hydrocarbons

A

The process take place at an oil refinery in steel fessels called crackers. In the cracker, a heavy fraction distilled from crude oil is heated to vaporise the hydrocarbons. The vapour is then either:

  • passed over a hot catalyst, or
  • mixed with steam and heated to a very high temperature

The hydrocarbons are cracked as thermal decomposition reactions take place. The large molecules split apart to from smaller, more useful ones.

36
Q

🟢 What happens when you Cracking Decane (Equations, Reactants, Products)

A

Decane, C10H22, is a medium sized alkane molecule. When it is heated to 500°C with a catalyst, it breaks down. One of the molecukes is produced is pentane, C5H12, which is used in petrol.

        H        H        H        H       H    
         |           |          |         |         |       H  -   C   -   C   -   C  -  C   - C  - H
         |            |         |         |         |   
        H        H        H        H       H

Propene and ethane are also made, which the chemical industry can use to produce polymers and other chemicals, such as solvents:

C10H22 (500°C + catalyst) —> (500°C + catalyst) C5H12 + C3H6 + C2H4

Decane (500°C + catalyst) —> (500°C + catalyst) Pentane + Propene + Ethene

37
Q

🟢 How does Cracking Produce different Types of Hydrocarbons and How are they different

A

Cracking produces different types of molecules. One of the molecules made in pentane. The last part of its name (-ane) shows that it is an alkane. Like all other alkanes, pentane is a saturated hydrocarbon and its molecules have as much hydrogen in them as possible.

The other molecules in this reaction have names that end slightly different. They end in ene (meaning it’s an alkene). The ending tells us that these molecules are unsaturated. Unsaturated compounds contain at least one double bond between their carbon atoms (e.g C=C) double covalent bond in their molecules. As carbon atoms form four covalent bonds, it means that the unsaturated akene molecules have two fewer hydrogen atoms in their molecules than the saturated alkane molecules with the same number of carbon atoms.

38
Q

🟢 How is Cracking Done in a Lab

A

Equipment:

  • Ceramic wool soaked in medicinal paraffin
  • Bunsen Burner (+ heat-proof mat, gauze, gas tap, e.c.t)
  • Broken pot (catalyst)
  • Delivery tube
  • Safety valve
  • Basin
  • Test Tube
  • Water
39
Q

🟢 What are the 2 ways to test for gaseous products from Cracking

A

Tests on the gaseous products for the experiment of cracking paraffin show that alkenes:

  • Burn in air (but no.t as well as equivalent small alkenes which are used as fuels)
  • React with bromine water, which is orange in colour, decolourising it
40
Q

🟢 What type of Hydrocarbon are more reactive and why

A

Alkenes are generally more reactive than alkanes. The reaction with bromine water is used as a test to see if an oragnic compound is unsaturated (like the alkenes with their C=C double bond.)

41
Q

🟢 What is a positive test for an unsaturated Hydrocarbon (+How do you distinguish between an Alkene and an Alkane)

A

A positive test for an unsaturated hydrocarbon is that it turns orange bromine water colourless.

The alkenes do not react with bromine water, so you can use this test to distinguish between an alkene and an alkane.

42
Q

🟢 Why does diesel oil colect above heavy oil byt below kerosene in the fractionating column

A

Diesel oil collects above heavy oil fuels as it has a lower boiling point range, as it has shorter chains of hydrocarbons in it’s fraction. Ot will collect below kerosene as it has a higher boiling point range and large hydrocarbons.

43
Q

🟢 Suggest two reasons why bitumen is not used as a fuel

A
  • It is less reactive/flammable/volatile

- It is too viscous

44
Q

🟢 Large hydrocarbon molecules in the diesel oil fraction are cracked to produce smaller hydrocarbon molecules

A

Conditions needed to crack hydrocarbon molecules from the diesel fractions includes putting the hydrocarbon molecules under a very high temperature and combining them with a catalysts for them to crack.

45
Q

🟢 Explain why large hydrocarbon molecules in the dieseloil fraction are cracked to produce smaller hydrocarbon molecules

A

Large hydrocarbon molecules are cracked to from smaller ones, as smaller hydrocarbons are more useful as they are better fuels, have lower boiling points, and burn cleaner flames. Another reason for producing smaller hydrocarbons is that they are in more demand.

46
Q

🟢 Complete the equation:

C15H32 —> C12H26 + ______

A

C15H32 —> C12H26 + C3H6

(GCSE) Chemistry (24 decks)

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