4.5 ORGANICS I Flashcards
Crude oil is a mix of what
Hydrocarbons
Define a hydrocarbon
A compound of hydrogen and carbon atoms only
What do each fraction of crude oil have in common
They are similar size hydrocarbons with similar boiling points
As the boiling points of fractions of crude oil increase, what trends occur
- The fractions get darker in colour
- The fractions get more viscous
What is the fraction with the lowest boiling point
Refinery gases
What is the fraction with the 2nd lowest boiling point
Gasoline
What is the fraction with the 3rd lowest boiling point
Kerosene
How many fractions of crude oil are there
6
What is the fraction with the 3rd highest boiling point
Diesel
What is the fraction with the 2nd highest boiling point
Fuel oil
What is the fraction with the highest boiling point
Bitumen
Why does the molecular mass increase, as the fractions boiling points increase?
They have more carbon and hydrogen atoms as the fractions go down the fractionating column
Use of refinery gases
Fuel for home cooking
Use of gasoline
Fuel for cars
Use of kerosene
Fuel for aircraft
Use of diesel
Fuel for trains
Use of fuel oil
Fuel for ships
Use of bitumen
Making roads
Describe the process of fractional distillation
- Heated crude oil vapours enter the column
- Vapours rise until they reach their boiling point, where they condense
- Different vapours condense at different heights due to their different boiling points
- Similar vapours condense together as a fraction
Define a fraction
Mixtures containing hydrocarbons that boil in a particular temperature range
What temperatures does kerosene boil at
250-350c
Alkane general formula
CnH2n+2
Name the alkanes according to the number of carbon atoms they have
- Methane
- Ethane
- Propane
- Butane
- Pentane
How is a displayed formula shows
Shows the position of every atom and bond
How is structural formula shown
The structure of molecules in one line
CH3 CH2CH2CH3
What are the functions of a homologous series
- Similar chemical reactions
- Trends in physical properties - (Boiling point)
- Same general formula - (Alkenes are CnH2n)
- Same functional group - (alkanes are all C-C)
Define an isomer
Molecules with the same molecular formula but different structural formulae
What are butanes 2 isomers
- Standard chain of carbon atoms with hydrogen off each one
- 3 carbon atoms in a chain with an extra off the middle carbon atom and 3 hydrogen atoms off that
What are pentanes 3 isomers
- Standard chain of carbon atoms with hydrogens off each one
- Chain of 4 carbon atoms with one atom off either of the inner 2 carbon atoms and 3 hydrogens off that one
- Chain of 3 carbon atoms with 2 carbon atoms off the central carbon atom, and 3 hydrogens off each one
What condition is needed for complete combustion
Excess oxygen
General equation for a complete combustion of alkanes
Alkane + Oxygen → Carbon dioxide + Water
How do you balance a hydrocarbon combustion equation
- Number of C in the hydrocarbon is the number of C on the opposite side (paired with oxygen)
- Half the number of H in the hydrocarbon is the number of H2O produced
- Half the number of O atoms on the products size to find the amount of O2 needed
What condition is required for incomplete combustion
Not enough oxygen
Instead of carbon dioxide, what is produced
Carbon monoxide and soot
What are the health problems associated with carbon monoxide and soot
CO - A toxic gas that lowers oxygen-carrying capacity of blood by binding to the hemoglobin
Soot (C) - Causes lung disease
Why is an incomplete combustion of alkanes less useful
Releases less energy
What 3 pollutant are released into the atmosphere when combusting alkanes, how are they created, and what effect do they have on the atmosphere
- Carbon Dioxide (CO2) - Formed as a direct product of combustion. A greenhouse gas that traps heat in the atmosphere and causes climate change
- Nitrogen Oxides (NOx) - Family of compounds formed when nitrogen from the air combusts in the hot environment of engines. Dissolve in rainwater to form acid rain which corrodes structures and is harmful to plant and aquatic life
- Sulphur Dioxide (SO2) - Formed when sulphur impurities in the fuel combust. Dissolve into rainwater to form acid rain
How do alkanes react with the halogens
By swapping one hydrogen atom for one halogen atom
Ethane equation for halogen reaction
C2H6 + Br2 → C2H5Br + HBr
What condition is needed for an alkane to react with a halogen and why
UV light - Provides the energy as the alkane is too unreactive
What type of reaction is a halogen-alkane reaction
Substitution - One H atom swaps with one Br atom
Displayed equation for a ethane-halogen reaction
What conditions are needed for cracking
- Temperature - 650c
- Aluminum Oxide (Al2O3) Catalyst
Could cracking be conducted without a catalyst
Yes - Far more energy would have to be provided
General equation for cracking
Long Alkane → Shorter Alkane + Alkene
What must you remember when making a cracking equation
It makes an alkane and an alkene, and the number of C and H atoms add up
General formula of alkenes
CnH2n
How many double bonds are in an alkene chain
1
Name the alkenes is order of number of C atoms
- Ethene
- Propene
- Butene
- Pentene
How is the double bond shown in the structural formula of an alkene
CH2=CHCH2CH3
Why are alkenes unsaturated
They have a C=C double bond
Why are alkanes saturated
They don’t have a C=C double bond (single only)
What is the equation for an alkene reacting with bromine (with ethene as an example)
C2H4 + Br2 → C2H4Br2
What physically happens in an alkene-bromine reaction
The C=C bond breaks and the Br atoms add in where it was
What type of reaction is an alkene -bromine reaction
Addition - You’re adding the bromine atoms into the alkene
Is UV light required for an alkene-bromine reaction
No - Alkenes are more reactive than alkanes
What type of bromine is needed for an alkene-bromine reaction
Bromine Water (or pure bromine liquid)
What colour is bromine water
Orange
How can you tell with bromine water is a mystery hydrocarbon is saturated or unsaturated
- Mix it with bromine water
- If it stays orange, there is no C=C bond, and it is saturated
- If it turn colourless, there is a C=C (unsaturated) and the bromine has been added to the alkene
When is an addition polymer formed
When moleucles with a C=C double bond add into chains
What are the small molecules and long chains called in addition polymers
Small - Monomers
Long - Polymers
Name the fractions of crude oil starting with the lowest boiling point
- Refinery gases
- Gasoline
- Kerosene
- Diesel
- Fuel oil
- Bitumen
How are repeating units drawn
One section of the polymer chain with brackets going through the outer bonds and a small n on the bottom right
How are polymers named
By putting a ‘poly’ in front of the monomer name (in brackets)
Monomer of poly(ethene)
Repeating unit of poly(ethene)
Uses of poly(ethene)
Drinks bottles and shopping bags
Monomer of poly(propene)
Repeating unit of poly(propene)
Uses of poly(propene)
Storage boxes and climbing ropes
Monomer of poly(chloroethene)
Repeating unit of Poly(chloroethene)
Uses of poly(chloroethene)
Wire insulation and drainpipes
Monomer of poly(tetrafluoroethene)
Repeating unit of poly(tetrafluoroethene)
Uses of poly(tetrafulroethene)
Non-stick coating
Addition polymers are inert. What does this mean
They are chemically very unreactive
What are the 3 disposal options for addition polymers
- Incinerate - use the energy to generate electricity
- Landfill - leave it there to go away
- Reuse/recycle - give it to someone who wants it or into the recycling bin
Displayed formula for alkene-bromine reaction (ethene)
