organics 1A-C Flashcards
1
Q
define a hydrocarbon
A
a compund containign hydorgen and carbon only
2
Q
define an alkane
A
- saturated compound - contain single carbon-carbon bonds only
- CnH2n+2
3
Q
define an alkene
A
- unsaturated compounds - contain double or triple carbon-carbon bonds
- CnH2n
4
Q
deifne an aliphatic compound
A
organic compound containing carbon and hydrogen joined together in straight chains, branched chains, or non-aromatic rings eg
….H H H
H-C-C-C-H
….H H H
5
Q
deinfe an alycyclic compound
A
organic compound contains one or more all-carbon rings which may be either saturated or unsaturated, but do not have aromatic character. in a circle each c bonded to 2 hydrogns
6
Q
deifne an aromatic compound
A
- organic compounds that contain a benzene ring or similar structures.
- carbon atoms with delocalised electrons
7
Q
whats a Homologous series
A
- a group of organic compounds that have the same functional group, the same general formula and the same chemical properties
- consecutive groups differ by -CH2- group
- Members have gradually changing physical properties, for example, boiling point, melting point and density
8
Q
whats a functional group
A
- charcetristic group of atoms that each member of homologous series has
- determine the physical and chemical properties of molecules
9
Q
whats a molecular formulae and give an example
A
- shows each atoms and number of each
- eg. butanol -C4H10O
10
Q
whats a displayed fromula and give an example
A
- Shows all atoms and bond
- eg. butanol
….H H H H
H-C-C-C-C-O-H
…H H H H
11
Q
whats a structural formula and give an example
A
- Shows all atoms bonded to a particular carbon grouped together
- eg. butanol CH3CH2CH2CH3
12
Q
whats a skeltal formula and give an example
A
- Shows bonds between each atoms only. Atoms other than C and H are shown
- eg: pentane - /\/\
13
Q
whats empirical formula
A
the simplest whole number ratio of the elements present in one molecule of the compound
14
Q
how cna we classify different types of reactions
A
- addition reaction
- substitution reaction
- elimination reaction
- hydrolysis reaction
- condensation reaction
15
Q
whats an addition reaction
A
an organic reaction in which two (or more) molecules combine to give a single product with no other products
16
Q
whats a substition reaction
A
a reaction that involves replacing an atom or group of atoms by another
17
Q
whats an elimination reaction
A
a reaction in which a small molecule (such as H2O or HCl) is removed from an organic molecule
18
Q
whats a hydrolisis reaction
A
a reaction in which a compound is broken down by water (it can also refer to the breakdown of a substance by dilute acids or alkali)
19
Q
whats a condensation reaction
A
a reaction in which two organic molecules join together and in the process eliminate small molecules (such as H2O or HCl)
20
Q
whtas a structural isomer
A
compounds with the same molecular formula but different structural formula
21
Q
whta are 2 types of structural isomers
A
- chain isomerisms
- positional isomerism
22
Q
whats a chain isomerism
A
- when compounds have the same molecular formula, but their longest hydrocarbon chain is not the same
- caused by branching
23
Q
whats a poistional isomer
A
The functional group can be located on different carbons
24
Q
A
25
whats a steroisomer
compounds that have the same atoms connected to each other, however the atoms are differently arranged in space
26
Z isomers
have groups on the same side of the double bond/carbon ring
- cis isomer
27
E isomers
have groups on opposite sides of the double bond/carbon ring
- trans isomer
28
do Z and E isomers have same properties
no - they have different chemical and physical properties
29
what is crude oil made up of
mixture of hydrocarbons containing alkanes, cycloalkanes and arenes
30
how are alkanes obtained
fractional distillation and cracking of crude oil
31
what is cracking
breaking down of large rchain alkanes into shorter chain alkanes and alkenes because they are more useful and in higher demand
32
what are the 2 types of craking
- thermal cracking
- catalytic cracking
33
conditions for thermal cracking
high temperatures (up to 1000 oC) and high pressure (up to 70 atmospheres) and produces alkanes and a lot of alkenes
34
conditions for catalytic cracking
uses a lower temperature (around 450 oC) and slight pressure in the presence of a catalyst such as a zeolite or aluminium oxide to produce mainly aromatic hydrocarbons
35
reforming of alkanes
converts straight chain alkanes into branched, cyclic and aromatic hydrocarbons and converts cyclic hydrocarbons into aromatic hydrocarbons
Reforming often uses a platinum catalyst
36
3 steps of free radical substitution
- inititation, free radicals made by UV braking the halogen bond, homolytic fission
- propogation step - maks firther freee radicals
- termination - 2 free raidcals colide
37
limitation of free radicals
- during the termination step, an unwanted molecule can be formed - impurities
- Excess chlorine present when reacted with methane in the presence of UV light will promote further substitution and could produce CH2Cl2, CHCl3, CCl4
- subsititution cna happen on different carbpns
38
definition of an electrophile
An electrophile is something which is attracted to electron-rich regions in other molecules or ions.
An electrophile must be something which carries either a full positive charge, or has a slight positive charge on it somewhere.
39
alkene + h2 --->
- forms an alkane
- conditions: solid Nicket catalyst + 150C
- eg. forming margarinw (staurated fats, solid) from vegetable oils (monounsaturated/plyunstaturated, liquid)
40
why si a solid nickel catluyst used in hydrogenation of alkenes
means that the products are easily separated from the reaction mixture.
41
alkene + H2O --->
- forms an alcohol
- conditions: heat (300-600C), H3PO4 catalyst - phosphoric acid
42
alkene + halogen --->
- forms a halogenoalkane
- conditions: room temp
- eg. Cl2 or Br2, add br2 (orange) to a colourless alkene you will form a colourless compound, if u use bromine water you will get a bromoalcohol
43
alkene + hydrogen halide --->
- forms monosubstituted haloalkane
- conditions room temperature
44
Oxidation-addition reaction with potassium manganate (VII)
- reagent - KMnO4 / H+ (acified potassium manangante (VII))
- conditions - room temperature
- alkene + H20 + [o] (oxidising agent) ---> forms a diol
45
def of markovnikovs rule
When an unsymmetrical alkene reacts with a molecule such as a hydrogen halide, there are often two possible products
46
hwo can u dispose of polymers
- recycling
- incineration
- feedstock recycling
-
47
descrieb how recycling cna be used ot remove polymers
- reduces the amount of waste that it going to landfill sites
- also reduce the use of finite resources, Lots of polymers are made from the products of cracking crude oil and it's fractions
- Recycling polymers is a time-consuming process as they have to be sorted into the different categories
- After sorting, the polymers are chopped, washed, dried, melted and then cast into pellets ready for use, However, mixed polymers can mean that this process is wasted as its produces an unusable mix of polymers
- Certain polymers can cause problems when recycling due to their chemical composition, e.g. PVC contains a large amount of toxic chlorine which can be released
48
describe process of incineration
- Some petroleum / natural gas derived polymers are still difficult to recycle
- Since they have a large amount of energy stored within the polymer chains, these polymers can be incinerated, This process can then be used to boil water and use the water vapour to turn turbines inside a power station, in a similar fashion to coal-fired power stations
- This process still causes environmental pollution as the carbon within the polymer can be released as carbon dioxide contributing to global warming, Other toxic waste products include hydrogen chloride and other chlorinated molecules from the combustion of PVC
49
describe process of feedstock recycling
Feedstock recycling is where waste polymers are broken down, by chemical and thermal processes, into monomers, gases and oils
These products are then used as the raw materials in the production of new polymers and other organic chemicals
The major benefit of feedstock recycling, compared to other methods of polymer disposal, is that it works with unsorted and unwashed polymers
50
hwo do chemists try to make desgignign polymers sustainable
- Use chemicals (reactants, solvents and catalysts) that are as safe and environmentally friendly as possible, They also aim to reduce the amount of chemicals used, in terms of physical quantities as well as actual number of chemicals
- Use renewable feedstock chemicals where possible
- Reduce the energy requirements for the reaction as well as increase the energy efficiency, which has both an environmental and financial bonus
- Improve atom economy / reduce the amount of waste byproducts
- Consider the lifespan of the polymer, which will incorporate the idea of the polymer being suitable for its use
51
how can we limit problems of polymer disposal
- waste gase from the incinerator are scrubbed/reacted with a base or carbonate, The base reacts with the acidic HCl gas, neutralising it
- biodegradable polymers - can be broken down over time by microorganisms, polyester and polyamide condensation polymers are considered to be biodegradable as they can be broken down using hydrolysis reactions, major advantage over the polymers produced using alkene monomers (polyalkenes), When polyesters and polyamides are taken to landfill sites, they can be broken down easily and their products used for other applications
- Compostable polymers are commonly plant based, Plant starch is being used in the production of biodegradable bin liners, Sugar cane fibres are replacing polystyrene in the production of disposable plates and cups, Compostable polymers degrade naturally leaving no harmful residues
52
equation complete combustion
alkane + O2 ---> CO2 + H2O
53
uesytion for incomplete combustion
alkane + O2 ---> CO + H2O
alkane + O2 ---> C + H2O
54
eqautions for oxidation of nitrogen
N2(g) + O2(g) → 2NO(g) (engine)
N2(g) + 2O2(g) → 2NO2(g) (atmosphere)
2NO2 + H2O ---> HNO2 + HNO3 (with water) - acid rain
- happens in car engines udner high temps and pressure
- Nitrogen oxides can also dissolve and react in water with oxygen to form nitric acid which is a cause of acid rain- causes damage to buildings, plants, aquatic life, land aniamsl inc humans
- Solid carbon particles (or particulates) released from incomplete combustion clump together to form soot which gradually falls back to the ground
55
particulates
- Solid carbon particles (or particulates) released from incomplete combustion clump together to form soot which gradually falls back to the ground
- Particulates can cause several problems:
- If they are inhaled they can damage the lungs and cause respiratory problems
- They can cover buildings and statues, making them look unclean and accelerating corrosion
- They can reflect sunlight back into space reducing the amount of light reaching the earth, this is called global dimming
56
eqautions for oxidation of sulfur
S + O2 --> SO2 (engine)
2SO2+ O2 ---> 2SO3 (stomosphere)
both SO2 and SO3 dissolbve in water to produce acid rain:
SO2 + H2O ---> H2SO3
SO3 + H2O ---> H2SO4
- produces acid rain
- auses resporatory ussyes
57
what are catalytic comvertors
- reduce the amount of pollutants released in car exhaust fumes
- contain a honeycomb of ceramic material coayed with ctalust to increase surface area therefore increaed rate of reaction and recues amoutn of expenisve metals used
- nitrogen oxides are reduced on the surface of the hot catalyst to form the unreactive and harmless nitrogen gas - 2CO (g) + 2NO (g) → 2CO2 (g) + N2 (g)
57
benefits of biofuels
Biofuels are often considered as carbon neutral
This is because as the plants grow they absorb carbon dioxide which is equivalent to the amount of carbon dioxide that will be released when they are burnt
This is not completely correct because carbon dioxide will also be produced in the refining and transport of the plants
Biodiesel and biogas can reduce the amount of waste going to landfill as the waste can be used to produce them
Biofuel production could provide money for less developed countries as they have the space to grow the crops required
57
negatives of biofuels
The cost of converting engines and machinery to run on biofuels instead of petrol / diesel
Many developed countries don't have the space to be able to produce enough plants to make the biofuels because the land is needed for food production
57
alyternatuve fuels
biofuels:
- Biodiesel - made by refining renewable fats and oils
- Bioethanol - made by fermentation
- Biogas - made / released when organic waste breaks down
