Unit 2 i) Hydrocarbons Flashcards

1
Q

Name the 3 fossil fuels?

A

Coal Oil Gas

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2
Q

Fossil fuels are finite. What does finite mean?

A

This means that they will eventually run out

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3
Q

What is combustion?

A

Combustion is a chemical reaction where substances burn in the presence of oxygen

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4
Q

What word is used to describe a reaction that gives out heat?

A

Exothermic

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5
Q

What is an endothermic reaction?

A

A reaction that takes in energy.

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6
Q

What is a fossil fuel?

A

Fuel from remains of long dead animals or plants. eg coal oil gas

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7
Q

What is the test for hydrogen?

A

Burns with a pop

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8
Q

What is the test for oxygen?

A

Relights a glowing splint

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9
Q

What is the test for carbon dioxide?

A

Turns lime water milky

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10
Q

What is a hydrocarbon?

A

A substance that contains only hydrogen and carbon

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11
Q

What is the simplest alkane?

A

Methane

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12
Q

What is the general formula of the alkanes?

A

CnH2n+2

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13
Q

What is a fuel?

A

A fuel is a substance which has stored energy. This energy is released when a fuel is burned

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14
Q

What is made when alkanes burn in excess oxygen?

A

Carbon dioxide and water

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15
Q

Name the alkanes and formulas from 1 to 8 carbons

A

Methane CH4 Ethane C2H6 Propane C3H8 Butane C4H10 Pentane C5H12 Hexane C6H14 Heptane C7H16 Octane C8H18

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16
Q

What do all alkenes contain?

A

A carbon to carbon double bond

17
Q

What is the simplest alkene?

A

Ethene C2H4

18
Q

What is the general formula for the alkenes?

A

CnH2n

19
Q

Name the alkenes and formulas for 1 to 8 carbons

A

Ethene C2H4 Propene C3H6 Butene C4H8 Pentene C5H10 Hexene C6H12 Heptene C7H14 Octene C8H16

20
Q

How are the carbon to carbon bonds in cycloalkanes?

A

All single

21
Q

What are isomers?

A

Isomers are substances with the same molecular formula but different structural formula eg cycloalkanes and alkenes

22
Q

What is the general formula for cycloalkanes?

A

CnH2n

23
Q

What does saturated mean?

A

All bonds are single

24
Q

How do you test for unsaturation?

A

To test if a hydrocarbon has double bonds we use bromine water. When bromine water is shaken with an unsaturated hydrocarbon the brown colour disappears

25
Q

What is crude oil?

A

Crude oil is a mixture of many hydrocarbon molecules

26
Q

What is distillation?

A

Distillation is two processes: evaporation followed by condensation

27
Q

What are the fractions when crude oil is distilled?

A

Fuel gases C1-C4 Petrol C8 Paraffin - jet fuel Diesel C16 - lorries and buses Bitumen

28
Q

As you go down the fractions what happens?

A

Molecular size increases Boiling point increases Viscosity increases Ignition temperature increases

29
Q

What process breaks down large molecules into smaller molecules?

A

Thermal cracking

30
Q

What is thermal cracking?

A

Breaking bonds to convert large molecules into smaller ones

31
Q

What is the shape of this?

A

Tetrahedral

32
Q

What is the shape of ammonia?

A

Pyramidal