C6.2 Organic Chemistry Flashcards

1
Q

Homologous series

A

Have common features such as same general formula and similar bonding

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2
Q

Alkanes general formula

A

CnH2n+2

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3
Q

Alkenes general formula

A

CnH2n

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4
Q

Complete combustion of Alkenes and Alkanes

A

hydrocarbon + oxygen -> carbon dioxide + water

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5
Q

Incomplete combustion of Alkenes/Alkanes

A

hydrocarbon + oxygen -> carbon + carbon monoxide + water

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6
Q

Alkanes only have single bonds between atoms

A

They are saturated

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7
Q

Alkenes have C=C double covalent bonds

A

They are unsaturated

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8
Q

Alkenes undergo addition reactions

A

An atom or group of worms combine with a molecule to form a larger molecule, with no other product

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9
Q

Alkenes addition reaction with bromine

A

Form colourless ‘dibromo’ compounds
e.g. ethene + bromine -> dibromoethane

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10
Q

Purpose of a functional group

A

Allows them to take part in a wider range of reactions such as addition reactions

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11
Q

Carbon monoxide

A

Produced due to incomplete combustion of hydrocarbons
Are a toxic gas and can cause suffocation

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12
Q

Test for alkenes (basic test for unsaturation)

A

Bromine goes from orange-brown to colourless when mixed with alkenes but not when mixed with alkanes

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13
Q

Complete and incomplete combustion of alcohols

A

Same as Alkenes and Alkanes

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14
Q

Carboxylic acids functional group

A

Carboxyl group (COOH)

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15
Q

Carboxylic acids general formula

A

CnH2n+1COOH

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16
Q

How are Carboxylic acids formed

A

When an alcohol reacts with an oxidising agent, such as potassium manganate (VII) solution
e.g. ethanol gets oxidised to ethanoic acid

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17
Q

How is ethanoic acid produced from ethanol

A

ethanol + potassium manganate (VII) + dilute sulphuric acid
warm it up
manganate ions (purple) are reduced to manganese (II) ions (pink) when acidified potassium manganate (VII) oxidises ethanol to ethanoic acid

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18
Q

Carboxylic acid + metal ->

A

Salt and hydrogen

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19
Q

Carboxylic acid + alkalis/bases ->

A

Salt and water

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20
Q

Carboxylic acids + carbonates ->

A

Salt, water, and carbon dioxide

e.g. ethanoic acid + sodium carbonate -> sodium ethanoate + water + carbon dioxide

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21
Q

How are crude oils formed?

A

They are a fossil fuel formed fro, the remains of marine organisms that lived millions of years ago which became buried deep into the sea bed after they died. Chemical reactions eventually turned them to crude oils.

22
Q

Problems with crude oil

A

It is a non renewable energy source meaning it is being used faster than it is produced. It’s a finite resource, they are no longer being made, or are being made extremely slowly.

23
Q

What are crude oils a mixture of?

A

Many different hydrocarbons

24
Q

Explain how the hydrocarbons in crude oil are separated by fractional distillation

A

Hydrocarbons have different boiling points.
- the more carbon atoms, the longer the molecule so the stronger the intermolecular force and the higher the boiling point
- fractionating column has a temperature gradient- hottest at the bottom
- as vapours rise, they condense and run off to be collected
- each fraction contains many substances with similar boiling points

25
Q

Features about atoms at the bottom of fractionating columns (crude oil)

A

They are joined together by covalent bonds which are stronger than intermolecular forces.

26
Q

At what scale is cracking carried out in?

A

A huge scale in oil refineries, but it can be done in a small scale in a laboratory using pieces of broken pot as the catalyst

27
Q

What is cracking?

A

A chemical reaction that converts large alkane molecules into smaller Alkanes and Alkenes molecules
e.g. octane -> hexane + ethene

28
Q

Conditions for cracking

A

600-700 degrees Celsius
Catalyst such as alumina or silica
Under these conditions, covalent bonds between atoms in large Alkanes molecules break

29
Q

Cons of large Alkanes

A
  • don’t flow easily
  • hard to ignite
30
Q

Fractional distillation produces…

A
  • more of the fractions with large molecules and high boiling points that can be sold
  • inadequate amounts of the small molecule fractions with low boiling points that are in high demand
31
Q

By using cracking, what can we do?

A

Help supply meet demand

32
Q

How much of crude oil is used for petrol, diesel, LPG etc? What is the rest used for?

A

90%. The rest is used in the chemical industry o make products like polymers.

33
Q

What are addition polymers?

A

Polymers formed by many monomer molecules being joined together

34
Q

Features of addition polymers

A
  • undergo addition reactions
  • monomers are Alkenes
  • to make the polymer you need high pressure and a catalyst
35
Q

What happens in condensation reactions?

A

Two molecules react to form one larger molecule and one smaller molecule, often water

36
Q

Example of condensation reaction
(Carboxylic acid) + (Alcohol)
Ethanoic acid + Ethanol -> ?

A

CH3COOH + C2H5OH -> CH3COOC2H5 + H20
Ethyl ethanoate + water

37
Q

Proteins are condensation polymers formed from amino acids. Each amino acid has two functional groups:

A

An amino group- NH2
A carboxyl group - COOH

38
Q

Conditions for condensation reactions

A

Do not require a catalyst and occur at room temp and pressure

39
Q

Examples of chemical cells

A

Batteries used in portable devices like phones or torches

40
Q

What type of reactions develop a p.d in a chemical cells two ends?

A

Exothermic

41
Q

How does a fuel cell produce electricity?

A

Through a chemical reaction between a fuel and oxygen, without combustion happening

42
Q

Hydrogen fuel cell reaction

A

Hydrogen reacts with oxygen to produce water vapour
2H2 (g) + O2 (g) -> 2H2O (g)

43
Q

Hydrogen reaction in hydrogen oxygen fuel cell

A

It’s the same overall reaction but in two separate reactions.
1) 2H2 (g) + -> 4H+ (aq) + 4e-
2) 4H+ (aq) + O2 (g) + 4e- -> 2H2O (g)

44
Q

What is a fuel cell?

A

A chemical cell which uses the reaction between a fuel cell and oxygen to produce a voltage

45
Q

What happens when an alkene reacts with hydrogen?

A

The hydrogen reacts with the double bonded carbons and adds across the double bond. The double bond becomes a C-C is single bond.

46
Q

What functional group must monomers have in order to join together to form an addition polymer?

A

A carbon-carbon double covalent bond

47
Q

Give an example of a small molecule that is lost during a condensation polymerisation reaction

A

Water (H2O)

48
Q

What type of condensation is formed when monomers containing two -COOH groups react with monomers containing two -NH2 groups?

A

Polyamide

49
Q

Why is cracking hydrocarbons necessary?

A

To produce shorter more useful hydrocarbons that are in higher demand.

50
Q

At what point does a chemical cell stop producing a p.d.

A

When all of one of the reactants has been used up.