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Chemistry > Topic 7: Organic Chemistry > Flashcards

Topic 7: Organic Chemistry Flashcards

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1
Q

What is a hydrocarbon?

A

Any compound that is formed from carbon and hydrogen atoms only

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2
Q

What is the general formula for alkanes?

A

CⁿH²ⁿ⁺²

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3
Q

Are alkanes saturated or unsaturated?

A

Saturated

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4
Q

Why are alkanes said to be saturated?

A

Each carbon atom forms 4 single covalent bonds

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5
Q

Do alkanes contain single or double bonds?

A

Single

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6
Q

What is a homologous series?

A

A group of organic compounds that react in a similar way

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7
Q

What are the first 4 alkanes?

A
  1. Methane
  2. Ethane
  3. Propane
  4. Butane
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8
Q

What is the trend as hydrocarbon chains get longer?
i) Viscosity
ii) Boiling point
iii) Flammability

A

i) Become more viscous (gloopy)
ii) Boiling point increases
iii) Become less flammable

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9
Q

What is the equation for the complete combustion of a hydrocarbon?

A

Hydrocarbon + oxygen —> carbon dioxide + water

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10
Q

During combustion, what happens to both carbon and hydrogen?

A

They are oxidised

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11
Q

Why are hydrocarbons used as fuels?

A

Due to the amount of energy they release when they combust completely

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12
Q

Describe how crude oil was formed [2]

A
  1. Formed from the remains of plants and animals, mainly plankton, that died millions of years ago and were buried in mud
  2. Over millions of years, with high temperatures and pressures, the remains turned to crude oil
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13
Q

Why is crude oil described as a non-renewable fuel?

A

It is being used up much faster than it is being formed

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14
Q

Why is crude oil described as a finite resource?

A

One day it will run out

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15
Q

What is crude oil made up of?

A

A mixture of lots of different hydrocarbons, most of which are alkanes

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16
Q

How are the different compounds in crude oil separated?

A

Fractional distillation

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17
Q

Describe how different compounds in crude oil are separated by fractional distillation [7]

A
  1. Oil is heated until it has turned into a gas
  2. The gas is fed into a fractionating column
  3. In the column there is a temperature gradient (it’s hot at the bottom and gets cooler as you go up)
  4. 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 bottom
  5. The shorter hydrocarbons have lower boiling points. They condense and drain out much later on, near the top of the column where it’s cooler
  6. You end up with a crude oil mixture separated out into different fractions
  7. 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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18
Q

What are the long hydrocarbons in fractional distillation used for?

A

Heavy fuel oil

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19
Q

What can heavy fuel oil be? [3]

A
  1. Heating oil
  2. Fuel oil
  3. Lubricating oil
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20
Q

What are the medium hydrocarbons in fractional distillation used for? [3]

A
  1. Diesel
  2. Kerosene
  3. Petrol
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21
Q

What are the short hydrocarbons in fractional distillation used for?

A

LPG (liquefied petroleum gas)

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22
Q

What does the petrochemical industry use hydrocarbons for?

A

Feedstock

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23
Q

Why are long-chain hydrocarbons not very useful?

A

They form thick, gloopy liquids which cannot be used as fuels

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24
Q

In what process are long-chain hydrocarbons made into short-chain hydrocarbons?

A

Cracking

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25
In cracking, what other hydrocarbon is produced?
Alkenes
26
What kind of reaction is cracking?
A thermal decomposition reaction
27
Define **'thermal decomposition'**
Breaking molecules down using heat
28
What are the 2 types of **cracking**?
1. Catalytic cracking 2. Steam cracking
29
Describe the process of **catalytic** cracking [3]
1. Heat the long-chain hydrocarbons to vaporise them 2. Pass the vapour over hot powdered aluminium oxide catalyst 3. The long-chain molecules split apart on the surface of the specks of catalyst
30
Describe the process of **steam** cracking [3]
1. Heat the long-chain hydrocarbons to vaporise them 2. Mix them with steam 3. Heat them at very high temperatures
31
When writing an equation for **cracking**, what is it important to do?
Balance the number of carbon and hydrogen atoms on both sides
32
What kind of bond does an **alkene** have?
C=C double bond
33
Why are alkenes said to be **unsaturated**?
The C=C double bond means that alkenes have two fewer hydrogens compared with alkanes containing the same number of carbon atoms
34
Why are alkenes much more **reactive** than alkanes?
The C=C double bond can open up to make a single bond, allowing the 2 carbon atoms to bond with other atoms
35
What are the first 4 **alkenes**?
1. Ethene 2. Propene 3. Butene 4. Pentene
36
What is the general formula for **alkenes**?
CⁿH²ⁿ
37
What is the test to distinguish between alkenes and alkanes?
Bromine water test
38
What will happen to bromine water in the presence of an **alkene**?
The solution will lose its orange colour and turn colourless
39
What will happen to bromine water in the presence of an **alkane**?
The solution will stay orange
40
What are the 3 types of addition reactions that **alkenes** can carry out?
1. Addition of hydrogen 2. Addition of steam 3. Addition of a halogen
41
Describe what happens in a **hydrogenation** reaction [2]
1. Hydrogen is reacted with an alkene (C=C double bond) 2. The C=C double bond is opened up and the equivalent, saturated alkane is formed
42
What has to be present in a **hydrogenation** reaction?
A catalyst
43
What happens when alkenes react with **steam**?
Water is added across the double bond and an alcohol is formed
44
How can **ethanol** (an alcohol) be made?
By mixing steam and ethene and passing it over a catalyst
45
Describe how you would isolate pure alcohol from ethanol, ethene and water [4]
1. Ethanol, ethene and water is present 2. The reaction mixture is passed from the reactor into a condenser 3. Ethanol and water have a higher boiling point than ethene, so both condense leaving the unreacted ethene 4. Ethanol and water is then separated by fractional distillation
46
What is a polymer?
Large molecule formed when lots of monomers join together
47
In **polymerisation**, what two conditions are needed? [2]
1. High pressure 2. Catalyst
48
What would be the name for an **ethene polymer** be?
poly(ethene)
49
What is the general formula for **alcohols**?
CⁿH²ⁿ⁺¹OH
50
What is the **functional group** for alcohols?
-OH
51
Name the first 4 **alcohols**
1. Methanol 2. Ethanol 3. Propanol 4. Butanol
52
What are the properties of alcohols i) Flammability ii) Solubility
i) Highly flammable (undergo complete combustion) ii) Soluble in water - neutral pH
53
What happens when alcohols are **oxidised**?
Produce carboxylic acid
54
What are **alcohols** used for? [2]
1. Solvents in industry 2. Fuels
55
Why are alchols used as **solvents** in industry?
Because they can dissolve substances that water can't disslolve e.g. oils and fats
56
What time of burner is ethanol (alcohol) used as fuel in?
Spirit burner
57
Positives of spirit burners [2]
1. Burns fairly cleanly 2. Non-smelly
58
What are the 3 main uses of **ethanol**?
1. As a chemical feedstock 2. As a biofuel 3. Used in alcoholic drinks
59
Advantages of producing ethanol from **ethene** and **steam**
The reaction is cheap and efficient
60
Disadvantages of producing ethanol from **ethene** and **steam**
Ethene is made from crude oil, which is non-renewable (could become expensive)
61
Advantages of producing ethanol from **fermentation**
Glucose used is renewable - won't run out
62
Disadvantages of producing ethanol from **fermentation**
Process can be slow
63
Fermentation equation
Glucose ---> ethanol + carbon dioxide
64
What is the functional group for **carboxylic acid**?
-COOH
65
What is produced when a **carboxylic acid** reacts with a **carbonate**?
Salt + water + carbon dioxide
66
# THINK: alcohols What is the general formula for **carboxylic acids**?
CⁿH²ⁿ⁺¹COOH
67
What is the functional group of an **ester**?
-COO-
68
What are **esters** formed from?
An alcohol and a carboxylic acid
69
What type of **catalyst** has to be used to produce an ester?
Acid catalyst
70
What is produced as a **by-product** when an ester is formed?
Water
71
What is ethyl ethanoate (ester) made from?
Ethanoic acid and ethanol
72
What are **esters** used in? [2]
1. Perfumes 2. Food colourings
73
Why is it called **condensation** polymerisation?
For each new bond that forms, a small molecule (water) is lost
74
Why are **condensation** polymers biodegradable?
Ester links can be broken down by microorganisms
75
What are the 3 **naturally** occurring polymers?
1. Amino acids 2. DNA 3. Carbohydrates
76
What are the 2 functional groups of an **amino acid**?
1. Amino group 2. Carboxyl group
77
What is the name for the polymers that amino acids form?
Polypeptides
78
What is one or more long-chains of polypeptides known as?
Proteins
79
What are the two polymer chains in DNA called?
Nucleotides
80
What small **molecules** are sugars made from? [3]
1. Carbon 2. Oxygen 3. Hydrogen
81
What long-chain polymers can **sugars** form?
Starch

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