C6.2 - Organic chemistry Flashcards
1
Q
What are there features of Alkanes?
A
They have :
- 4 bonds ( the maximum number a carbon atom can make )
- single bonds ONLY
2
Q
What are Alkanes ?
A
Alkanes are a homologous series of saturated hydrocarbons with the general formula of C nH 2n+2
3
Q
what does saturated mean ?
A
that something contains single bonds only
4
Q
what does unsaturated mean ?
A
that something contains double bonds only
5
Q
what is a hydrocarbon ?
A
something that contains hydrogen and carbon atoms only
6
Q
what is a homologous series?
A
A homologous series has the same general formula and have similar chemical properties
7
Q
what is viscosity ?
A
the strength of intermolecular forces
8
Q
how does the size of alkanes effect their properties ?
A
As the size of an alkane increases, its boiling point and melting point increase, as do its viscosity and density
9
Q
Name the features of small Alkanes ?
A
- low boiling points
- High flammability
- Clean cleanliness of flame
- Low viscosity
10
Q
Name the features of large Alkanes ?
A
- High boiling points
- Low flammability
- Sooty cleanliness of flame
- High viscosity
11
Q
What are the uses of Alkanes ?
A
1 ) As fuels
2 ) For Cracking
12
Q
When does complete and incomplete combustion occur + formulae ?
A
Complete - in a good supply of oxygen –> COv2 + Hv2O
Incomplete - in a poor/ limited supply of oxygen –> CO or C + Hv2O
13
Q
Explain how Alkanes are used for fuels?
A
Alkanes burn well, releasing a lot of heat energy, eg :
Complete combustion : CHv4 + 2Ov2 —> COv2 + Hv2O
Incomplete combustion : CHv4 + 1½Ov2 —> CO + 2Hv2O
THIS IS BALANCED
14
Q
Explain how Alkanes are used for cracking?
A
long alkanes —> short alkanes + alkene
short alkanes are used as fuels
alkenes are used to make polymers
15
Q
How can we balance combustion equations?
A
Using the CHO method:
balance carbon atoms first, hydrogen atoms second and lastly oxygen atoms
16
Q
Name the Alkanes based on the number of carbons?
A
1 - methane
2 - ethane
3 - propane
4 - butane
17
Q
Draw the displayed formula of the displayed formula of alkanes ( methane , ethane, propane, butane and pentane )
A
18
Q
What are alcohols ?
A
Alcohol’s are the homologous series containing the functional group - O - H
19
Q
Name the alcohols based on the number of carbons?
A
1 - methanol
2 - ethanol
3 - propanol
4 - butanol
20
Q
What is the general formula for alcohol’s ?
A
Cvn Hv2n+1 OH
21
Q
Draw the displayed formula of alcohols ( methanol , ethanol, propanol, butanol and pentanol )
A
22
Q
What are the uses of alcohols?
A
- Fuels
- Solvents
- Ethanol in ALCOHOLIC drinks
23
Q
Explain how Alcohols are used for fuels?
A
Like alkanes they burn in oxygen ( or air ):
Complete combustion : Cv2Hv5OH + 3Ov2 —> 2COv2 + 3Hv2O ( producing water vapour and carbon dioxide )
Incomplete combustion : Cv2Hv5OH + 2Ov2 —> 2CO + 3Hv2O ( producing carbon monoxide and water vapour )
24
Q
Explain why Alcohols are used for solvents?
A
Since they have low boiling points and are therefore volatile ( easily vaporises )
25
What are the dangers of using ethanol in ALCOHOLIC DRINKS ?
all alcohols are toxic so if there is too much ethanol in a space of time = it can result in death
26
What are Alkenes ?
Alkenes are a homologous series of unsaturated ( contains double carbon bond ) hydrocarbons with the general formula C nH 2n
27
What is the general formula of Alkenes?
C nH 2n
28
Name the alkenes based on the number of carbons?
2 - ethene
3 - propene
4 - butene
5 - pentene
29
Draw the displayed formula of Alkenes ( ethene, propene, butene, pentene )
30
What are the rules of displayed formula for Alkenes?
- C=C per Alkene
- C has max 4 bonds
31
Name features of Alkenes in reactions ?
- Alkenes are very reactive ( due to presence of the C=C double bond which undergoes addition reactions
- In addition reactions, the C=C double bond becomes a C-C single bond and other atoms join onto the two C atoms
- Alkenes do also burn, but they are rarely burned as they are ( a ) too valuable for making polymers and ( b) tend to undergo incomplete combustion with smoky flame
32
How can double C=C bonds in Alkenes be tested?
By testing it with Bromine water =
Bromine is only orange when bonded to another Bromide atom since it's diatomic. When an Alkene reacts with Bromine water it turns from orange to colourless proving that Alkenes react and decolourise Bromine water proving the existence of a C=C bond, a part of an alkene.
33
Look at Alkenes and how to draw them when they react with something else?
OK
34
What do Alkenes need to react with to make Alkanes and Alcohols?
Alkanes = at 150o with nickel catalyst ) - Hv2\
Alcohols = ( at high temp with concentrated phosphoric acid catalyst ) Hv2O
35
Name the Carboxylic acids based on the number of carbons?
1 - methanol acid
2 - Ethnic acid
3 - propanoic acid
4 - Butanoic acid
36
What is the general formula of Carboxylic acids?
Cvn Hv2n+1 COOH
37
What are the reactions of Carboxylic acids?
1 ) Metal + Acid ---> Salt + Hydrogen
eg. Magnesium + ethanoic acid ---> Magnesium ethanoate + hydrogen
2 ) Metal carbonate + acid ---> salt + water + carbon dioxide
eg. Sodium carbonate + ethanoic acid ---> sodium ethanoate + water + carbon dioxide
3) Alkali + acid --> salt + water
38
What is crude oil?
A mixture of hydrocarbons
39
How is crude oil separated, how does it work?
- First the crude oil is heated/vaporised at around 350C ( mark ) and fed into a fractionating column which has a temperature gradient, meaning that Its hotter at the bottom and cooler at the top. ( mark )
- The crude oil then evaporates and rises, long chain hydrocarbons with higher boiling points will condense at lower fractions in the column, whilst shorter chain hydrocarbons with lower boiling points will condense at higher fractions in the column ( Mark).
- These separated fractions now hold range of differently sized liquid hydrocarbons which will be collected through pipes.
Some hydrocarbons with very low boiling points such as natural gases will escape out of the top of the column whilst some hydrocarbons with very high boiling points do not vaporise such as bitumen, which leaves through the bottom of the column.
40
Are the fractions pure substances or mixtures ? How can you tell?
Mixtures - since it contains a range of different hydrocarbons ( different amount of atoms )
41
Name the features of small hydrocarbons ?
- low boiling points
- High flammability
- Clean cleanliness of flame
- Low viscosity
42
What are hydrocarbons ?
A compound containing only carbon and hydrogen
43
Name the features of large hydrocarbons ?
- High boiling points
- Low flammability
- Sooty cleanliness of flame
- High viscosity
44
the hydrocarbons in crude oil have different properties. Which of these properties does separation by fractional distillation depend on?
the hydrocarbons boiling point
45
How to crude oils come to be ?
- Fossil fuels found underground
- Dead plant and animal remains settle at the
bottom of the ocean
- Sediment builds up over time
- heat and pressure increases
- Over million of years are turned into crude oil
46
What kind of resource is crude oil?
A finite resource
47
What is cracking ?
Cracking is a chemical reaction that breaks/ converts longer alkane molecules into shorter alkane molecules ( which then can be used as Fuel ) and alkene.
48
how can alkanes be broken down?
Through cracking :
1) Vaporise and pass over hot catalyst
2) Mix with steam at high temp
49
Draw the set up of cracking alkanes?
Catalyst can be either aluminium or zeolite
50
What is produced when a long alkane undergoes cracking ?
short alkanes and alkenes
51
Tips for drawing polymers ?
- You don't draw the whole polymer, only a repeated section ( repeat unit )
- Include trailing bonds suggesting there is more...
- Brackets LAY OVER the trailing bonds
- n for monomer is placed before, for polymer its drawn after
52
Look how to draw polymers correctly ?
k bro
53
What are the features of a homologous series?
- Same general formula
- Have similar chemical properties
- A trend in physical properties
- The same functional group
54
Name some natural occurring polymers?
- DNA
- Starch
- Glucose
- Cellulose
55
Describe the structure of DNA?
DNA is a polymer made of monomers called nucleotides, they contain :
- Phosphate
- Deoxyribose
- Bases ( four different ones, A - T , G - C )
56
What are the different types of polymers?
- Addition polymers
- Condensation polymers
57
What is addition polymerisation ?
Formation of long chain molecules from lots of small molecules joining together with no products forming
58
What is condensation polymerisation ?
Formation of long chain molecules from lots of small molecules joining together with another small molecule ( eg. water ) produced as well
59
What holds the bases in DNA together ?
Intermolecular forces called hydrogen bonds
60
Describe the structure of proteins ?
Proteins are polymers made up of monomers called amino acids
61
Describe the structure of Carbohydrates ?
Carbohydrates are compounds of oxygen, hydrogen and carbon. They include simple sugars such as deoxyribose and sucrose.
62
When carboxylic acid and alcohols react what is produced ?
Esters
63
What are addition polymers ?
Addition polymers are formed by the joining up of many monomers and only occurs in monomers that contain C=C bonds
64
What are condensation polymers ?
They are polymers formed by condensation reactions, a monomer molecule for a condensation polymer needs two different functional group, one at each end
65
Give some examples of synthetic polymers ?
polyethene, polypropene, polychloroethene
66
What are the conditions to carry out addition polymerisation ? These are not needed for condensation polymerisation
A catalyst at high temperature and high pressure
67
what is an amino group ?
- NH2
68
Name the 4 bases found in DNA ?
Adenine, Thymine, Cytosine, Guanine
69
What is a carboxyl group
- COOH
70
What is an ester group
- COO
71
What is an Amide group
-CONH-
72
Compare the structure of DNA, Proteins and Carbohydrates.
In your answer, include the similarities and differences between them.
They are polymers. They are made up of monomers.
DNA monomers are nucleotides (Phosphate, sugar-deoxyribose, organic base). Proteins are made from amino acids. carbohydrates are made from simple sugars (glucose, & sucrose)
DNA contains four different monomers / nucleotides. Proteins contain about 20 different monomers / amino acids - higher
Sucrose contains two different simple sugars / glucose and fructose
73
Write a word equation for making polyamide/ an amide ?
amine ( two amino groups ) + carboxylic acid ( two carboxyl group ) --> polyamide + water
74
State some advantages of fuel cells
- They have no moving parts
- They are compact.
- They are lightweight.
- Zero emissions of CO2 from cars (H2O only product)
- Easy access to hydrogen and oxygen from decomposition of water
75
What are the disadvantages of fuel cells
- The method we currently use to produce hydrogen uses fossil fuels which produce pollutants and are running out.
- Fuel cells often use poisonous catalysts which have to be disposed of safely when the fuel cell reaches the end of its life
75
Write the reaction at the cathode
4H+(aq) + O2 (g) + 4e- → 2H2O(g)
76
Write the reaction at the anode
H2(g) → 2H+ (aq) + 2e-
77
What are polyesters made from
- A carboxylic acid ( with two carboxyl groups, also known as dicarboxylic acid )
- An alcohol ( with two hydroxyl groups also known as diol )
78
How are proteins formed?
Proteins are condensation polymers formed from amino acids.
Amino acids have two different functional groups: Amino and a carboxyl group
79
What are the two types of condensation polymers?
Polyester and polyamides
80
Describe the method of how Nylon-6,6 is made?
- Carefully pour the solution in organic solvent on top of the solution in water without mixing them.
- Nylon-6,6 will be formed at the later where the two solutions meet
- Extract the nylon by slowly lifting it out of the beaker with a pair of tweezers
- Collect the nylon as a thread by wrapping it around a rod as it’s pulled from the beaker
81
If potassium magnate added to an alcohol, what happens ?
Potassium magnate is a strong oxidising agent so alcohol is then oxidised and turned in the carboxylic acid?
82
What colour is potassium magnate ?
Purple
83
What is the colour of Bromine water ?
Orange
84
Explain the process of cracking ? ( Use decane as an example )
The long chain hydrocarbon, decane is heated up at a high temp and high pressure to break strong covalent bonds and produce a shorter chain alkane and alkene.
