Organic Chemistry Pt 2 Flashcards
Polymerisation definition
The process of producing long chain molecules from small molecules
Addition polymerisation definition
How monomers can join together to form very long chain molecules called polymers
Properties of polythene
Light, flexible and resistant to attack by acids and alkalis
Uses of polythene
Cling film, plastic bags, bottles
Properties of PVC
tough, durable, waterproof and good insulator
Uses of PVC
Electric cables, guttering, drain pipes
Name four benefits of plastics
Less dense than other materials
Resistant to chemicals and water
Excellent insulation properties
Extremely long lasting
Name the monomer that is used to make polythene
Ethene
What type of reaction is used to make polythene
Addition polymerisation
Give the molecular formula and structural formula of propene
C3H6
Write a symbol equation to show how PVC is made from vinyl chloride
See sheet
Advantages of landfill
Local treatment so less transport is needed
Landscape can be re-landscaped after use
Disadvantages of landfill (2)
Wastes land
Polluting gases released
Advantages of incineration (2)
- less waste going to landfill
- heat energy can generate electricity
Disadvantages of incineration
- ash residue is toxic
- polluting gases are released
What are biodegradable plastics made from
Maize starch
Explain the term non-biodegradable
Materials that cannot be broken down by microbes
Give three ways that councils are promoting the recycling of plastics
- imposed on household to pay for dumping plastics
- councils run information sessions
- Council provides collection points in supermarkets and provide on support kerb side recycling
Complete Combustion of alcohols
- Burn with a clear blue flame
- Heat is released
Homologous series of alcohols general formula :
CnH2n+1OH
Describe ethanol
- A water soluble miscible liquid
Molecular and structural formula of methanol
CH3OH
H
H- C - O - H
H
Molecular formula of ethanol
C2H5OH
H H
H - C - C - O - H
H H
Propan-1-ol molecular formula
C3H7OH
H. H. H.
H - C - C - C - O - H
H. H. H
Propan-2-ol molecular formula
C3H7OH
H. OH H
H - C - C - C - H
H. H. H
State of alcohols as room temperature
Liquid
Describe the preparation of ethanol from sugars by fermentation (4)
- Yeast is added to water and sugar in the absence of air
- It is left in a warm, dry place (36 degrees) for a few days
- Fermentation occurs giving ethanol and bubbles of carbon dioxide
- Reaction is brought about by the enzyme zymase which is present in yeast
What does ethene and steam produce ?
Ethanol
Describe the oxidation of alcohols when exposed to air
By leaving ethanol in air over time it will be oxidised to ethanol acid by oxygen
Describe the reaction of ethanol with acidified potassium dichromate solution (4)
- Potassium dichromate (K2Cr2O7) is a common oxidising agent
- Reacting it with alcohols is carried out in a test tube with the alcohol mixed with acidified potassium dichromate solution
- The test tube is then placed in a beaker of warm water
- A colour change from orange to green is observed
Structural formula of oxidised Methanol
Methanoic acid
O
//
H - C
\
OHStructural formula of oxidised ethanol
Ethanoic acid
H O
| //
H - C - C
| \
H. OH
Structural formula of oxidised propan-1-ol
Propanoic acid
H. H O
| | //
H - C - C - C
| | \
H. H OH
recall the molecular formula of carboxylic acids and what they form
- Methanoic acid HCOOH forms methanoate salts - HCOO- - Ethanoic acid CH3COOH forms ethanoate salts - CH3COO- - Propanoic acid CH3CH2COOH forms propanoate salts - C2H5COO- - Butanoic acid CH3CH2CH2COOH forms butanoate salts - C3H7COO-
State at room temperature and pressure of the carboxylic acids
Liquid
Are carboxylic acids weak?
carboxylic acids are weak acids as they are only partially ionised in solution
Reaction of ethanoic acid with sodium carbonate
Observations - Bubbles of gas are formed, white solid disappears and a colourless solution forms
2CH3COOH + NA2CO3 —> 2CH3COONa + H2O + CO2
Only carboxylic acids will release carbon dioxide when sodium carbonate is added to a sample
Reaction of propanoic acid with magnesium
Observations - Bubbles of gas produced, heat released, grey solid disappears and a colourless solution forms
2C2H5COOH + Mg —> (C2H5COO)2Mg + H2
Reaction of butanoic acid with sodium hydroxide
Observations - Heat is released and solution remains colourless
CH3CH2CH2COOH + NaOH —> C3H7COONa + H2O
How is combustion of fuels a major source of atmospheric pollution (3)
• combustion of hydrocarbons producing carbon dioxide, which leads to the greenhouse effect causing sea level rises, flooding and climate change;
• incomplete combustion producing carbon monoxide (toxic) and soot (carbon particles), which cause lung damage
• presence of sulfur impurities in fuels, which leads to
acid rain damaging buildings, destroying vegetation and killing fish
Reactions of Alkanes, alkenes, alcohols and carboxylic acids when warmed with acidified potassium dichromate solution
Alkane - Solution remains orange
Alkene- Solution remains orange
Alcohol - Solution changes from orange to green
Carboxylic acid - solution remains orange
How is the atmospheric pollutant Sulfur dioxide produced and problems it causes (3)
- Many fuels contain Sulfur impurities which burn and produce acidic Sulfur dioxide
- Sulfur dioxide reacts with water in the atmosphere to form sulfurous acid which falls as acid rain
- acid rain can damage buildings and vegetation
How is soot formed and what problems it causes
- Incomplete combustion of fuels
- Carbon particles pollute the air and cause lung damage
What happens as propan-1-ol undergoes oxidation
Forms propanoic acid
Distinguishing different organic families using bromine water
solid sodium carbonate
potassium dichromate
Alkane - N N N
Alkene - Y N N
Carboxylic acid - N Y N
Alcohol - N N Y
How is carboxylic acid weak?
They have the typical reactions of an acid with metals, bases and carbonates. However they will react more slowly
Main advantage of recycling addition polymers? (1)
- Thermoplastics can be remoulded
What process is used to obtain a concentrated solution of ethanol from the fermentation solution
Ethanol can be separated from yeast by fractional distillation
Combustion of methanol
Complete and incomplete
2CH3OH + 3O2 —> 2CO2 + 4H2O
CH3OH + O2 —> CO + 2H2O
