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OCR gcse ChEMisTry > C6.2 > Flashcards

C6.2 Flashcards

1
Q

What are hydrocarbons

A

Hydrocarbons are compounds containing only hydrogen and carbon atoms.

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2
Q

Why do alkanes form a homologous series

A

They form a homologous series as they have features in common

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3
Q

What are the carbon atoms joined to each other by and are alkanes saturated or unsaturated

A

They are joined together by single covalent bonds, they are saturated.

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4
Q

What do alkanes burn in and what do they produce

A

The burn in oxygen in air, carbon atoms are oxidised to carbon dioxide and hydrogen atoms oxidised to water.

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5
Q

When does incomplete combustion occur

A

Incomplete combustion occurs when there is a poor supply of oxygen.

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6
Q

What are the products of incomplete combustion

A

Carbon monoxide, water and carbon are produced.

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7
Q

What is the homologous feature of an alkene

A

They have one double bond

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8
Q

What is the general formula for alkenes

A

CnH2n

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9
Q

What is the general formula for alkanes

A

CnH2n+2

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10
Q

When there is one carbon what is the prefix

A

Meth

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11
Q

When there is two carbons what is the prefix

A

Eth

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12
Q

When there is three carbon what is the prefix

A

Prop

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13
Q

When there is four carbon what is the prefix

A

But

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14
Q

When there is five carbon what is the prefix

A

Pent

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15
Q

When there is six carbon what is the prefix

A

Hex

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16
Q

What is a functional group

A

A functional group is an atom, group of atoms or type of bond in a molecule responsible for the characteristic reactions of the substance.

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17
Q

What is the functional group of alkenes

A

C=C

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18
Q

What is the test for an alkene or alkane

A

Add bromine water, if it’s an alkene the solution turns colourless as bromine reacts with alkenes but not alkanes.

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19
Q

When do alkenes undergo addition reactions with hydrogen

A

When there is a nickel catalyst present.

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20
Q

What is the functional group of an alcohol

A

-OH (hydroxyl) group

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21
Q

What is the general formula for an alcohol

A

CnH2n+1(OH)

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22
Q

What can alcohols undergo

A

Complete and incomplete combustion with the same products as before

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23
Q

What is the functional group for carboxylic acids

A

-COOH

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24
Q

General formula for carboxylic acids

A

CnH2n+1COOH

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25
Q

Draw ethanoic acid

A
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26
Q

How are carboxylic acids formed

A

They are formed when alcohols react with oxidising agents such as potassium manganate solution.

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27
Q

What reactions can carboxylic acids take part in

A

.Metals to produce salts and hydrogen
.Alkalis and bases to produce salts and water
.Carbonates to produce salts, water and CO2

28
Q

What is the colour change when potassium manganate reacts with ethanol

A

The colour changes from purple and are reduced to pink.

29
Q

What is crude oil

A

Crude oil is a fossil fuel. It was formed from the remains of marine organisms that lived many years ago. They were buried deep in the sea bed after they died. Chemical reactions turned them into crude oil.

30
Q

What two types of resources is crude oil

A

It is a finite resource and is also a non-renewable resource

31
Q

How are the different alkanes in crude oil seperated

A

Using fractional distillation

32
Q

Why does fractional distillation work

A

This works because the alkanes have different boiling points

33
Q

What do larger alkanes have

A

The larger the molecules the stronger the intermolecular forces and the higher the boiling point.

34
Q

What is the process of fractional distillation

A

Crude oil is heated and the vapours are pipe into the bottom of a fractionating column. This has a temperature gradient - hotter at the bottom than the top. They then condense into a liquid where it’s cool enough. The separated parts of crude oil are called fractions. Each fraction contains substances with similar melting points.

35
Q

What is cracking

A

A chemical reaction that converts large alkane molecules into smaller alkane and alkene molecules

36
Q

What is the process of cracking

A

Heating oil fractions to a high temperature and passing it over a hot catalyst of alumina or silica. The covalent bonds between the large alkane molecules break.

37
Q

What are the characteristics of large alkanes

A

They have high boiling points are viscous and are difficult to ignite.

38
Q

Why is cracking used

A

Fractional distillation produces more of the larger molecule fractions and less small molecule fractions.

39
Q

What are polymers made up of

A

They are made up of smaller monomers joined together.

40
Q

What are the conditions needed for addition polymerisation

A

A high temperature and catalyst

41
Q

What can all alkanes be used for

A

Addition polymerisation

42
Q

Draw poly ethene

A
43
Q

What are the monomers in DNA

A

The nucleotides

44
Q

What are the nucleotides made of

A

A sugar (deoxyribose), a phosphate, an organic base (A,C,T,G)

45
Q

What are the four different bases for DNA

A

Adenine
Guanine
Cytosine
Thymine

46
Q

What do the nucleotides join end to end to form

A

One long strand of DNA

47
Q

What do the two strands of DNA do

A

They spiral around each other in opposite directions. Hydrogen bonds then form between the bases. This forms DNA.

48
Q

What are proteins made from

A

Proteins are made from amino acids (monomers)

49
Q

What do amino acids have at the end of them

A

Each amino acid has a functional group at the end so they can join each other end to end.

50
Q

What are carbohydrates compounds of

A

They are compounds of carbon, hydrogen and oxygen. They include sugars such as sucrose and complex carbohydrates such as starch.

51
Q

What happens in condensation reactions

A

In a condensation reaction two larger molecules react together to form one larger molecule and one smaller molecule.

52
Q

What happens when carboxylic acids react with alcohols

A

They form esters as the -COOH react with -OH to produce water and the ester group -COO- which links together the rest of the carboxylic acid and alcohol.

53
Q

What are condensation polymers

A

Condensation polymers are polymers formed from condensation reactions.

54
Q

What does a monomer need to have for this to occur

A

It needs to have a functional group at both ends of the monomer.

55
Q

What are polyesters made from

A

They are made form dicarboxyls and dialcohols. They are polyesters as they contain the functional group -COO.

56
Q

What are polyamids made from

A

They are made from a dicarboxyl and a diamine. This produces polyamids with the functional group -CONH-

57
Q

Difference between addition polymerisation and condensation polymerisation

A

Happens with a catalyst at high temperatures and pressure. However condensation polymerisation can happen without a catalyst at room temperature and pressure.

58
Q

What happens in a battery

A

Exothermic reactions in the cell develop a potential difference between two ends When it’s connected to an electrical circuit a current flows through the cell.

59
Q

When does a P.D stop being produce

A

It produces electricity until the reactants are used up.

60
Q

How does a fuel cell produce electricity

A

It produces electricity through a chemical reaction between a fuel and oxygen, without combustion occuring.

61
Q

What is the reaction between hydrogen and oxygen

A

It’s an exothermic reaction that produces water vapour.

62
Q

What happens at the anode of a fuel cell

A

Oxidation occurs and hydrogen loses electrons.
2H2 (G) -> 4H+ (aq) + 4e-

63
Q

What happens to the hydrogen ions after this

A

They pass through a proton exchange membrane to the other side of the fuel cell, the electrons travel through the external circuit to the other side of the fuel cell.

64
Q

What happens at the other side of the fuel cell

A

Hydrogen ions combine with oxygen and electrons at the other side to form water vapour. 4H+ + O2 + 4e- -> 2H2O

65
Q

What happens at the cathode of the fuel cell

A

At the cathode reduction occurs.

OCR gcse ChEMisTry (16 decks)

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