C6.2 Flashcards
1
Q
What are alkanes?
A
They are saturated hydrocarbons that form a homologous series
2
Q
What does it mean a molecule to be saturated?
A
The molecule only has single carbon bonds
3
Q
What does it means for an molecule to be a hydrocarbon?
A
The atom only contains hydrogen and oxygen
4
Q
What are the first 4 alkanes?
A
Methane
Ethane
Propane
Butane
5
Q
What is the general formula for alkanes?
A
CnH2n+2
6
Q
What do you have to remember when drawing the displayed formulae?
A
Carbon can form 4 bonds
Hydrogen can form 1 bond
7
Q
What type of bonds form in alkanes?
A
Covalent bonds
8
Q
How do alkanes react in a good supply of oxygen?
A
They perform complete combustion
Carbon dioxide and water are formed
9
Q
How do alkanes react in a poor supply of oxygen?
A
Incomplete combustion
Carbon monoxide (CO) and water
10
Q
What is the pattern of boiling point with alkanes?
A
The boiling point increases with an increasing number of carbon atoms
11
Q
What are alkenes?
A
They are unsaturated hydrocarbons that form a homologous series
12
Q
What does a molecule being unsaturated mean?
A
The molecule has a carbon to carbon double bond
13
Q
What is the general formula for alkenes?
A
CnH2n
14
Q
What are the first 4 alkenes?
A
Ethene
Propene
Butene
Pentene
15
Q
How do you model alkenes?
A
Draw all the atoms but make sure there is 1 carbon to carbon double bond
16
Q
What is a functional group?
A
An atom, group of atoms, or type of bond in a molecule that is responsible for the characteristics of the reaction
17
Q
What is an addition reaction?
A
When an atoms or group of atoms combine with a molecule to form a larger molecule with no other product
18
Q
How would you test for saturation?
A
Add bromine water
19
Q
How does bromine react with alkenes and why?
A
It turns colourless because of the carbon to carbon double bond
20
Q
How can alkenes become alkanes?
A
Perform an addition reaction between an alkene and hydrogen in the presence of a nickel catalyst
21
Q
What is the functional group in alkenes?
A
The carbon to carbon double bond
22
Q
What are alcohols?
A
They form a homologous series
23
Q
What is the functional group in alcohols?
A
The hydroxyl group - OH
24
Q
What is the general formula for alcohols?
A
CnH2n+1, OH
25
What are the first 4 alcohols?
Methanol
Ethanol
Propanol
Butanol
26
How do alkenes react?
Combustion just like alkanes
Complete combustion in oxygen - CO2 + H2O
Incomplete combustion in low oxygen - CO + H2O
27
How do alcohols react?
Complete combustion in the presence of lots of oxygen
Incomplete combustion in the presence of a poor amount of oxygen
28
What is produced in the complete combustion of alcohols?
Water (as water vapour) and carbon dioxide
29
What is formed in the incomplete combustion of alcohols?
Carbon monoxide and water (as water vapour)
30
What is the functional group for carboxylic acid?
Carboxyl group - COOH
31
What is the general formula for the carboxylic acids?
CnH2n+1, COOH
Where methanoic acid (the first one) does not have the Carbon at the beginning
32
How are carboxylic acids formed?
When alcohols react with oxidising agents, such as potassium manganate(VII)
33
How do carboxylic acids react?
Typical of acids so react:
With metals to produce salts and hydrogen
With alkalis and bases to produce salts and water
With carbonates to produce salts, water and carbon dioxide
34
What is crude oil?
A non-renewable fossil fuel and it is being used faster than it is formed
35
What does more carbon atoms in an alkane molecule mean?
The larger the molecules
The stronger the intermolecular forces
The higher the boiling point
36
What is crude oil made of?
Complex mixture of hydrocarbons (mainly alkanes) that are separated by fractional distillation
37
What are the attributes of a fractionating column?
The higher you go up it, the lower the temperature
Smaller alkane molecules at the top
38
How are alkanes separated from crude oil in a fractionating column?
There is a temperature gradient in the fractioning column so vapours cool as they rise through the column and then they condense into liquid state if they reach a part that is cool enough
39
What are fractions in a fractionating column?
The separate parts of the crude oil
40
What does each fraction contain?
Many substances with similar boiling points - highest boiling point at bottom and lowing boiling point at top
41
What is cracking?
A chemical reaction that converts large alkane molecules into smaller alkane and alkene molecules
42
What happens during cracking?
Covalent bonds between atoms in the large alkane molecules break under certain conditions
43
What are the conditions required for cracking?
High temperature (600 - 700 degrees Celsius)
Hot catalyst of alumina or silica
44
What type of molecules are useful as fuels and why?
Fractions with small alkane molecules as they flow more easily and are easier to ignite (as suppose to large alkane molecules which are the opposite)
45
What are examples of useful products produced by cracking?
Diesel
Petrol
LPG
46
Why is crude oil important?
It is used to produce fuels which are high in demand
47
What are addition polymers?
Polymers that are formed by monomers undergoing addition reaction as they have a carbon to carbon double bond
48
What are examples of molecules that can become addition polymers?
All alkenes
49
What are the conditions needed for addition polymerisation reactions?
High pressure
Catalyst
50
What do monomers undergo to become addition polymers?
Addition polymerisation reactions
51
How does the name of a monomer change become a polymer?
Ethene —> poly(ethene)
52
What are the 3 biological polymers?
DNA
Protein
Carbohydrates
53
What is DNA made up of?
Monomers called nucleotides
54
What does each nucleotide consist of?
A phosphate group
A sugar called deoxyribose
An organic base
55
What are the 4 different bases in a nucleotide?
Adenine
Thymine
Cytosine
Guanine
56
How is a DNA strand comprised?
Nucleotides join together end by end to form 1 strand of DNA - the sugar of 1 nucleotide bonds to the phosphate group of the next nucleotide
57
How are two strands of DNA bonded!
They spiral around each other in opposite directions and intermolecular forces called hydrogen bonds form between the complimentary bases on opposite strands
58
What are the complementary base pairs?
Cytosine and Guanine
Adenine and Thymine
59
What are proteins made of?
Monomers called amino acids
60
How many natural occurring amino acids are there?
20
61
How do amino acids join together?
Each amino acid has a reactive functional group at each
62
What do different protein molecules contain?
Different numbers of amino acids joined together in different combinations
63
What are carbohydrates?
Compounds of carbon, hydrogen and oxygen
64
What do carbohydrates include?
Simple sugars (deoxyribose and sucrose)
Complex carbohydrates (starch)
65
What is sucrose made of?
Two simple sugars - fructose and glucose
66
What is starch made of?
Very many simple sugars joined together
67
What is a condensation reaction?
A reaction in which 2 molecules react together to form 1 larger molecule and 1 smaller molecule (often water)
68
What do carboxylic acids and alcohols form?
Organic compounds called esters and water
69
What are condensation polymers?
Polymers formed by condensation reactions
70
What is different about a monomer molecule for a condensation polymer?
They need 2 different functional groups at each end
71
What is an example of condensation polymers?
Proteins formed by amino acids - each amino acid has an amino group (-NH2) and a carboxyl group (-COOH)
72
What is an amide group?
It is how the remaining parts of each monomer are joined together (for amino acids)
73
What is the symbol for the amide group?
-CONH-
74
What are the two main types of artificial condensation polymers?
Polyesters
Polyamides
75
What are polyesters made from?
A carboxylic acid with 2 carboxyl groups
An alcohol with 2 hydroxyl groups
76
Why is a polyester called a polyester?
Because they contain main ester groups (-COO-)
77
What are polyamides made from?
A carboxylic acid with 2 carboxyl groups
An amine with 2 amino groups (-CONH-)
78
What is an example of a polyester?
PET - used to make clothing and fizzy drink bottles
79
What is an example of a polyamide?
Nylon - used to make clothing and carpets
80
What are the conditions for addition polymerisation?
A catalyst
High temperature
High pressure
81
What are the conditions for condensation polymerisation?
No catalyst needed
Room temperature
Room pressure
82
What are examples of chemical cells?
Batteries in portable devices such as mobile phones and torches
83
How does a chemical cell work?
Exothermic reactions in the cell develop a voltage between its two end - when the cell is connected to an electrical circuit, a current flows through the cell and the components of the circuit
84
When will a chemical cell stop working?
When one of the reactants get used up - the cell “goes flat” and can’t provide a voltage
85
What is a hydrogen-oxygen fuel cell?
A fuel cell produces electricity through a chemical reaction between a fuel and oxygen - without combustion happening
86
What happens in a hydrogen-oxygen fuel cell?
Hydrogen reacts with oxygen in an exothermic reaction to produce water vapour
87
What are the 2 overall reactions that happens in a hydrogen-oxygen fuel cell?
2H2 (g) + O2 (g) —> 2H2O (g)
4H+ (aq) + O2 (g) + 4e- —> 2H2O (g)
88
What happens to the reactions inside a fuel cell?
They are separated into 2 reactions - one on each side of the cell
89
What happens to the hydrogen on 1 side of a fuel cell?
Hydrogen molecules lose electrons and become hydrogen ions.
90
What is the equation for the following statement - Hydrogen molecules lose electrons and become hydrogen ions?
2H2 (g) —> 4H+ (aq) + 4e-
91
How does the hydrogen of one side travel to the other side of a fuel cell?
Hydrogen ions pass through a ‘proton exchange membrane’ to the other side
Electrons travel through the external circuit to the other side
92
What is the equation for the following statement - hydrogen ions combine with oxygen and electrons to form water vapour?
4H+ (aq) + O2 (g) + 4e- —> 2H2O (g)
93
What happens to the oxygen at the other side of a fuel cell?
Hydrogen ions combine with oxygen and electrons at the other side to form water vapour
