Organic Chemistry Part One Flashcards
What is crude oil a mixture of ?
Hydrocarbons
How is crude oil removed from the earth ?
By drilling
Explain why the hydrocarbons in crude oil can be separated
They have different boiling points and therefore are separated into different fractions using fractional distillation. The shorter the molecules (less carbon atoms) the lower the temperature that the fraction condenses at
The different fuels evaporate and condense at different temperatures
Define a hydrocarbon
A compound or molecule that consists of hydrogen and carbon only
Define renewable resources
They are continuously supplied by nature as they are used by the consumers,
Give three examples of renewable resources
Hydroelectric Wind, Waves And Solar energy
Define non-renewable resource
Fuels that are finite and once they are used up they cannot be replaced
What is fractional distillation?
A continual process of evaporation and condensation. The fractionating column works continuously with heated crude oil piped in at the bottom and various fractions being constantly tapped off at different levels where they condense
The bottom of the fractionating column is warmer than the top
Boiling range for refinery gas
-160 to 20 degrees
Uses for refinery gas (2)
Fuel for gas ovens and GAZ chemicals
Boiling range for petrol (gasoline)
20 to 70 degrees
Uses for petrol (2’
Fuel for vehicles and chemicals
Boiling range for naphtha
70 to 120
Boiling range for paraffin (kerosine)
120 to 170 degrees
Uses for paraffin (2)
Jet engines and paraffin for heating
Boiling range for diesel oils
170 to 230 degrees
Boiling range for fuel oil and lubricating oil
230 to 350
Uses for fuel oil and lubricating oil (3)
Fuel for ships, factories and central heating
Boiling range for tar (bitumen)
Above 350 degrees
Uses for tar (bitumen) (2)
Used to surface Roofs, waterproofing
Describe the three stages in petro-chemical industry (3)
- First Stage of the petrochemical industry involves extracting crude oil from its source
- it is then transported to refineries and fractional distillation separates it into different hydrocarbons
- The hydrocarbons obtained by fractional distillation are used not only as fuels but can also be used in the manufacture of dyes, plastics, fertilisers etc
Name three environmental concerns for crude oil
- transport of crude oil can result in spills and leakages
- drilling for oil in the sea bed can also result in leaks
- air pollution is caused by burning fossil fuels as carbon dioxide is produced
The element which all fossil fuels contain is
Carbon
Cracking definition
Cracking is a process that is carried out by the oil industry which involves the breakdown of larger saturated hydrocarbons (alkanes) into smaller more useful ones, some of which are unsaturated (alkenes)
Draw heptane being broken down into an ethene and pentane
Sheet
Name four traits of a homologous series
- same general formula
- similar chemical properties
- gradual change in physical properties
- differ by CH2 unit
What is a homologous series ?
A family of organic compounds that have the same general formula, show similar chemical properties, show a gradation in their physical properties and differ successfully by a CH2 group
Name the alkanes general formula
CnH2n+2
Methane molecules formula
CH4
Methane structural formula
H
H- C - H
H
Colour and state of methane, ethane, propane and butane at room temperature
Colourless gas
Ethane molecular formula
C2H6
Propane molecular formula
C3H8
Butane molecular formula
C4H10
What kind of bonding is present in alkanes
Single covalent
Why are alkanes less reactive organic molecules
They do not have a functional group
Why do alkanes make good fuels
They burn very exothermically and therefore make food fuels
What is propane gas used for
Portable hair tongs
Define combustion
The reaction in which a fuel reacts with oxygen producing oxides and releasing heat
Chemical products of combustion are (2)
Carbon dioxide and water
What colour will the gas be during combustion ?
Clear blue flame with no sooty flame
Complete combustion word equation
Hydrocarbon + oxygen —> carbon dioxide + water + energy
Write the balanced symbol equation for the complete combustion of methane
CH4 + 202 —> CO2 + 2H20
Incomplete combustion word equation
Hydrocarbon + oxygen —> carbon monoxide + water
Give the balanced symbol equation of the incomplete combustion of methane
2CH4 + 3O2 —> 2CO + 4H20
In terms of bond making and bond breaking explain why burning butane in oxygen is an exothermic reaction
- Bonds are broken in the reactants, butane and oxygen. This requires energy
- Bonds are formed in the products, carbon dioxide and water. This releases energy.
- In this reaction more energy is given out making bonds of products water and carbon dioxide than has been put in to break bonds of reactants butane and oxygen
- overall the reaction is exothermic
Name the general formula of alkenes
CnH2n
What kind of bonding is present in alkenes ?
At least one double covalent bond between two of the carbon atoms
Alkenes are called …
Unsaturated hydrocarbons
What colour of flame do alkenes burn with ?
Orange flame
Molecular formula of ethene
C2H4
Propene molecular formula
C3H6
But-1-ene molecular formula
C4H8
But-2-ene molecular formula
C4H8
Colour of observation of alkanes and bromine water
Stays orange
Alkenes and bromine water reaction
Turns from orange to colourless
What is the addition reaction of ethene with hydrogen
This is called hydrogenation because hydrogen adds across the C=C double bond
Why when ethene is hydrogenated does it become ethane ?
Ethene has 4 hydrogen’s and so adding another hydrogen molecule of H-H to it would make C2H6
Conditions for hydrogenation
Nickel catalyst in 150 degrees
What is the addition reaction between ethene and steam called
Hydration reaction
Describe the fractions in fractional distillation
- They are largely a mixture of compounds of formula CnH2n+2
- which are members of the alkane homologous series
Uses of naphtha (2)
Used to manufacture chemicals and plastics
Uses for diesel
Fuel for Diesel engines
Describe combustion (5)
- The chemical products are carbon dioxide and water
- It is an oxidation reaction
- the reaction is exothermic
- complete combustion means burning in an excess of air, when all the carbon turns to carbon dioxide
- Gas Burns with a clear blue flame that is clean, no-sooty flame
Test involving combustion
The combustion of a hydrocarbon candle wax
What solution is present in the test for complete combustion?
Limewater
Describe incomplete combustion (4)
- incomplete combustion occurs when oxygen is limited in supply
- it produces carbon monoxide and water
- Sometimes soot (Carbon) is also produced particularly with larger alkenes
- the flame is smoky due to soot
Why is carbon monoxide dangerous ?
It is a toxic gas that combines with haemoglobin in the blood, reducing its capacity to carry oxygen
What is a functional group
A functional group is a reactive group in a molecule
Alkenes State at room temperature
Colourless gas
Why are alkenes not normally used as fuels? (2)
- They are very valuable
- Can be used to make polymers or as a starting material for other chemicals
Describe the complete combustion of alkenes
They will completely combust in a plentiful supply of oxygen
Draw the functional group of alkenes
R R
\ /
C = C
/ \
R RDraw the functional group of alcohols
R — O
\
H
Draw the functional group of carboxylic acids
O
||
C
/ \
R OHWhy are alkanes less reactive?
They don’t have a functional group
Describe the observations for the experiment to determine the presence of a C=C bond
Cyclohexane - Brome water stays orange
Cyclohexene - Bromine water changes from orange to colourless
Write the formula of the product of the reaction of ethene with bromine, hydrogen and steam
C2H4Br
C2H
What do conditions of fermentation of yeast, warmth (35 degrees), sugar, water and absence of O2 create?
Ethanol
What happens when ethanol is oxidised and what can be produced from it? (4)
- Ethanol is oxidised with acidified potassium dichromate into ethanoic acid
- Adding Magnesium to ethanoic acid produces magnesium acetate and hydrogen (CH3COO)2Mg + H2)
- Adding sodium hydroxide to ethanoic acid produces sodium acetate and water (CH3COONa + H2O)
- Adding calcium carbonate to ethanoic acid produced calcium acetate, carbon dioxide and water (CH3COO)2Ca + CO2 + H2O
How is ethanol achieved from hydrocarbons? (3)
- Refining And catalytic cracking turns hydrocarbons into alkenes
- Alkenes are hydrated with steam(H2O), phosphoric acid at 330 degrees and 70atm
- This produces ethanol
How is polythene achieved from hydrocarbons (2)
- Refining And catalytic cracking produces alkenes
- The process of addition polymerisation joins together many molecules of ethene together to form polythene
Reaction between ethene and steam
C2H4 + H2O —> C2H5OH
Ethene + steam —> ethanol
Reaction between ethene and hydrogen
C2H4 + H2 —> C2H6
Suggest why bromine mustn’t come into contact with water
Very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment
Adding bromine water to alkene
H H
| |
H - C - C - H
| |
Br Br
Orange to colourless
List all the fractions and boiling points in the fractionating column (7)
- Refinery gas -160 to 20
- Petrol (gasoline) 20-70
- Naphtha 70-120
- Paraffin (kerosine) 120-170
- Diesel oils 170-230
- Fuel oil and lubricating oil 230-350
- Tar (bitumen) above 350
What is the functional group of alkenes, alcohols and carboxylic acids
Alkenes C=C
Alcohols -OH
carboxylic acids =O
- C
\
OH
Effect of carbon content in an organic compound
The higher the percentage carbon content by mass of an organic compound, the more orange the flame will which it burns in air. A lower carbon content causes the flame to be blue
Testing products of combustion
- Cool the gases and a colourless liquid will condense - Add this liquid to anhydrous Copper(ii) Sulfate, any water present will change the anhydrous Copper (ii) Sulfate from white to blue
- bubble the gases through limewater - any CO2 present will change the limewater from colourless to milky
