SC20 Fuels Flashcards

1
Q

Define hydrocarbon

A

A compound made of hydrogen and carbon and is used as a raw material

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2
Q

Why is crude oil finite?

A

It’s formed underground over millions of years from the buried remains of plants and animals

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3
Q

Top Fraction - Gases

A

used in domestic heating and cooking

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4
Q

2nd Fraction from top - Petrol

A

used as fuel in cars

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5
Q

3rd Fraction from top - Kerosene

A

used as a fuel in aircraft

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6
Q

4th Fraction from top - Diesel

A

used as a fuel in some cars and larger vehicles eg. trains

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7
Q

5th Fraction - Fuel oil

A

used as a fuel for larger ships and power stations

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8
Q

6th Fraction - Bitumen

A

used to surface roads and roofs

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9
Q

How does fractional distillation work?

A

Crude oil is heated until most of it has turned to gas. The gases enter a fractionating column with a temp. gradient. The longer hydrocarbons have high bps so turn into liquids and drain out the bottom

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10
Q

Why do properties of different fractions differ?

A

Each fraction has a different length of hydrocarbons, so they each have different properties because of this

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11
Q

Define homologous series

A

A family of molecules with the same general formula and share similar chemical properties

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12
Q

Why do alkanes form a homologous series?

A

They all share the same general formula, with a difference of CH2

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13
Q

Define complete combustion

A

Burning hydrocarbons with plenty of oxygen to produce CO2 and water

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14
Q

Define incomplete combustion

A

Occurs when a hydrocarbon is burnt with a limited supply of oxygen

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15
Q

Why is carbon monoxide toxic?

A

It combines with red blood cells and stops your blood from carrying oxygen around the body. This can cause fainting, a coma or even death

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16
Q

Problems with incomplete combustion

A

It produces carbon monoxide, and carbon in the form of soot

17
Q

How are harmful products made in incomplete combustion?

A

Without enough oxygen, the products contain less oxygen, which forms toxic products

18
Q

How is sulfur dioxide made?

A

When fossil fuels are burned, they release sulfur dioxide which comes from sulfur impurities in the fossil fuels.

19
Q

What causes acid rain?

A

When sulfur dioxide mixes with the clouds, forming dilute sulfuric acid

20
Q

Effects of acid rain

A

Causes lakes to become acidic and animals to die. Kills trees, damages limestone buildings and stone statues, and can also make metal corrode

21
Q

Define oxides of nitrogen

A

Created from a reaction between the nitrogen and oxygen in the air, caused by the energy released by combustion reactions

22
Q

What do oxides of nitrogen cause?

A

Contribute to acid rain, and cause photochemical smog that causes air pollution

23
Q

Advantages to using Hydrogen as a fuel

A
  • Clean fuel
  • Only waste product is water
  • Renewable
24
Q

Disadvantages to using Hydrogen as a fuel

A
  • Need a special, expensive machine
  • Expensive
  • Uses energy from other sources (energy often from burning fossil fuels)
25
Define cracking
Cracking turns long saturated alkane molecules into smaller unsaturated alkene and alkane molecules - it's a form of thermal decomposition
26
Why are alkanes saturated and alkenes unsaturated?
Alkanes are saturated because all bonds have been formed. Whereas alkenes are unsaturated because all possible bonds that can be formed, haven't been
27
Why is cracking necessary?
Cracking helps meet the higher demand for shorter chained molecules, rather than having longer chained molecules that aren't commonly needed