organic chemistry Flashcards
1
Q
Homologous series
A
A group of compounds that can all be represented with the same general formula, same functional group and trend in physical properties.
2
Q
Hydrocarbon
A
A compound containing hydrogen and carbon only
3
Q
Functional group
A
A group of atoms that determine how a compound typically reacts.
4
Q
Isomer
A
A compound that has the same molecular formula but a different structural formula.
5
Q
Crude oil
A
A mixture of hydrocarbons
6
Q
Fuel
A
A substance that, when burned, releases heat energy
7
Q
Saturated
A
Contains single covalent bonds only
8
Q
Alkanes
A
Compounds in crude oil which are saturated hydrocarbons
9
Q
As the length of the carbon chain of alkanes increases…
A
Boiling point increases Become more viscous Less flammable Darker in colour Produce more soot
10
Q
Describe fractional distillation
A
- Crude oil is vaporised
- The fractioning column is hot at the bottom and cold at the top
- The fraction condenses in the fractioning column Jen the temperature is equal to its boiling point
- Short chains= low boiling points = come out at top
- The liquid is then piped off and the rest of the gases continue to rise.
11
Q
List the fractions from coolest to hottest
A
Refinery gases Gasoline Naphtha Kerosene Diesel oil Fuel oil Residue
12
Q
List tests for water
A
- Anhydrous CuSO4 (white solids -> blue solid)
- Cobalt chloride (blue solid -> pink solid)
- Measuring boiling point (100C)
13
Q
Equation of combustion
A
Hydrocarbon + O2 -> CO2 + H2O
14
Q
Use of refinery gases
A
Bottled gases
15
Q
Uses of gasoline (petrol)
A
Fuel for cars
16
Q
Uses of naphtha
A
Making chemicals
17
Q
Uses of kerosene
A
Aircraft fuel
18
Q
Uses of diesel oil
A
Fuel for cars, lorries, buses
19
Q
Uses of fuel oil
A
Fuel for ships and power stations
20
Q
Uses of residue
A
Bitumen for roads and roofs
21
Q
How is cracking carried out?
A
Hydrocarbons are vaporised then passed over a catalyst (silica/alumina) at a high temperature (600C- 700C)
22
Q
Compared to alkanes, alkenes:
- boiling point
- saturated/unsaturated
- flammability
- viscosity
- bromine water test
- volatility
A
Have lower boiling points Are unsaturated Are more flammable Are less viscous Will turn from orange-> colourless in bromine water Are more volatile
23
Q
Paraffin oil represents
A
Alkanes
24
Q
The product represents
A
Alkenes
25
Definition of a monomer
A molecule that can join with many others to make a polymer
26
Problems with disposal of addition polymers
Plastics are inert and non biodegradable (cannot be broken down by living organisms).
One way to get rid of plastic waste is by burning it, however this can release toxic gases.
27
What makes alkenes unsaturated?
They do not only have single bonds and contain a carbon (C=C) double bond.
28
Bromine test for alkenes
| result + explanation
Orange -> colourless
| Dibromoalkenes are produced because the C=C bond breaks
29
Alkane test for bromine water result + explanation
No colour change because alkanes are highly unreactive.
30
Why is cracking necessary?
It helps to match the supply of fractions with the demand for them. Shorter chained hydrocarbons have a higher demand in the industry than longer chained hydrocarbons.
31
Definition of biodegradable
Can be broken down by living organisms
32
Alkenes functional group
>C=C
33
What conditions are needed for the reaction of steam with alkenes?
- 300 C
- 60-70 atm pressure
- catalyst of phosphoric acid
34
What kind of reaction do alkanes undergo and what conditions are needed for this to happen?
Substitution reactions - UV light is needed
35
What kind of reactions do alkenes undergo?
Addition reactions
36
Explain the addition reaction between alkenes and bromine
- the bromine molecule breaks up and ‘adds’ to the alkene using the electrons from the double bond
- the product is now saturated
- alkanes cannot do this as they don’t have a double bond
37
What functional group do alcohols contain?
-OH
38
Word equation for the combustion of ethanol
Ethanol + oxygen -> carbon dioxide + water
39
Symbol equation for combustion of ethanol
C2H5OH + 3O2 -> 2CO2 + 3H2O
40
Three ways ethanol can be oxidised:
- burning in air or oxygen (complete combustion)
- reaction with oxygen in the air to form ethanoic acid (microbial oxidation)
- heating with potassium dichromate (VI) in dilute sulfuric acid to form ethanoic acid
41
Word equation for oxidation of ethanol to form ethanoic acid as a result of microbial action.
Ethanol + Oxygen -> ethanoic acid
42
Colour of potassium dichromate solution before + after heating
Orange
| Green
43
Observations of oxidation of ethanol with potassium dichromate
Product smells like vinegar
44
Word equation of ethanol being oxidised with potassium dichromate
Ethanol + oxygen -> ethanoic acid + water
45
Ethanoic acid formula
CH3COOH
46
Give 2 ways to manufacture ethanol
- reacting ethene with steam
| - fermentation of glucose
47
Conditions needed for reaction of ethene with steam
- 300 C
- 60-70 atm pressure
- phosphoric acid
48
Fermentation of glucose word equation
Glucose -> ethanol + CO2
49
Conditions needed for fermentation of glucose
Sugar in water, yeast, temperature of 30-40C, absence of air
50
Why must there be an absence of air for fermentation of glucose to occur
Otherwise the ethanol will oxidise and become sour
51
Why must temperature be 30-40C for fermentation of yeast?
Yeast is a living organism and its optimum temperature for fermentation is 35C. At higher temperatures the reaction nearly stops as the enzyme is denatured.
52
Difference between fermentation and hydration of ethene in terms of the type of process.
Fermentation - inefficient batch process where everything is put into a container and left until fermentation is complete.
Hydration- an efficient continuous flow process.
53
Difference between fermentation and hydration of ethene in terms of the rate of reaction.
Fermentation - very slow
| Hydration- very rapid
54
Difference between fermentation and hydration of ethene in terms of the quality of product.
Fermentation- produces very impure ethanol which needs further processing
Hydration- produces much purer ethanol
55
Difference between fermentation and hydration of ethene in terms of the reaction conditions.
Fermentation- uses gentle temperatures and atmospheric pressure
Hydration- uses high temperatures and pressures, needing a lot of energy input
56
Difference between fermentation and hydration of ethene in terms of the use of resources.
Fermentation- uses renewable resources based on plant material
Hydration- uses finite resources based on crude oil.
57
Method to make an ester
- 1cm ethanoic acid + 2cm ethanol + 2 drops of concentrated sulphuric acid (acting as catalyst)
- hot water bath 5 mins
- 20 cm3 sodium carbonate in beaker then pour solution in it (this will neutralise any remaining acid)
58
Definition of a weak acid
An acid that forms a small number of hydrogen ions when it dissolves in water. Weak acids only partially dissociate into ions.
59
Are carboxylic acids strong or weak acids?
Weak
60
What is vinegar
An aqueous solution containing ethanoic acid
61
Functional group of an ester
-COO-
62
Properties of an ester
Esters are volatile compounds with distinctive smells and are used as food flavourings and in perfumes
63
How to make an ester (NOT METHOD)
ALCOHOL + CARBOXYLIC ACID
64
How to form a condensation polymer
DICARBOXYLIC ACID + DIOL
65
Solution to problems with polymers
To produce more types of biodegradable polymers. The polyesters that are biodegradable are referred to as biopolyesters.
66
Example of biopolyesters advantages and disadvantages
Corn starch polymers
+ renewable
+ biodegradable
+ does not release toxic gases when burned
+ can be recycled
- large areas of land are needed to grow the crops and corn used
- this reduces the amount available as a food crop
67
Definition of an addition polymer
Monomers join together to make one long molecule (polymer) with no other product
68
Definition of condensation polymer
Monomers join together to make a polymer plus a small molecule
