Organic Chemistry Flashcards
What is a hydrocarbon
Any compound made of only hydrogen and carbon
What is a functional group?
Atoms or groups of atoms in a molecule that determine chemical properties of a compound
What is a saturated compound
A hydrocarbon with no double bonds (alkanes)
What is an unsaturated compound?
A hydrocarbon with one or more double bond
What is the general formula for alkanes
C(n)H(2n)+2
What is the general formula for alkenes?
C(n)H(2n)
What are the first five alkanes
Methane, ethane, propane, butane, pentain
What are the first 5 alkenes
Ethane, propane, butane, pentane, hexane
Why does the boiling point of alkanes increase with chain length?
- more atoms and bonds on one line need a larger force to separate
Why are short chain hydrocarbons more volatile ?
- have a lower boiling point so they evaporate easier
What is more flammable , short chain or long chain hydrocarbons?
Short chain alkanes
What is meant by refined
Separated
How is crude oil formed
Plankton is compressed by heart and pressure typically by the ocean and over a long time produces crude oil
What is meant by oxidisation?
When oxygen bonds to a hydrocarbon to make H2O
What is combustion
Burning (rapid reaction between a substance and oxygen
What is the difference between complete and incomplete combustion?
In incomplete combustion there is not enough oxygen to create carbon dioxide, so carbon monoxide is produced instead
What is the equation for combustion?
Hydrocarbon fuel + oxygen = carbon dioxide + water
What are the properties of complete combustion?
- blue flame
- little / no soot
What are the properties of incomplete combustion?
- yellow flame
-soot (carbon)
What are the properties of carbon monoxide?
- colourless
- odourless
- very toxic (staves body of oxygen as CO binds better to hoemoglobin than oxygen so starves blood of oxygen
What are the problems with particulates (soot)
- creates smog - dark clouds cause global dimming
- respiratory problems caused when inhaled
What is meant by airpollution
Products of incomplete combustion
What are the problems with nitrogen oxide and sulfur dioxide?
- damages lungs if inhaled
- gets in clouds and forms dilute acids (acid rain)
What are the problems with acid rain?
- damages buildings
- corrodes metals
- damages plants
- makes soil acidic
What are the early atmospheric gases?
- carbon dioxide,
- water vapour
- methane
- ammonia (NH3)
What are the proportions of the earths atmosphere today?
- nitrogen 78%
- oxygen 21%
- argon 0.9%
- carbon dioxide 0.037%
How was the early atmosphere formed?
- volcanoes dispersed volatile chemicals that made up the atmosphere
- CO2 kept earth hot
- volcanoes release co2 and h2o
- H2O condensed to form seas
- co2 dissolved in seas and became locked up in rocks
- photosynthesis by primative plants produced oxygen
- levels of co2 decreased, levels of oxygen increased
What is the greenhouse effect?
- Sun rays go through the earths atmosphere
- reflect of the earth
- rebound into the atmosphere to keep the earth warm like a greenhouse
What method can be used to see how much CO2 levels change over time
Ice cores- counting bubbles and measuring them for CO2
What creates methane?
- agriculture
- decomposition of rubbish in landfill
What creates CO2?
- fossil fuels
- deforestation
What are the effects of climate change?
- polar ice caps melt ( causing rising sea levels)
- extinction of species living in cold climates as temp getting too hot
- change in rainfall (droughts and flood)
- change in species distribution
What do the names of alkanes end in?
- ane
What do the names of alkenes end in?
-ene
What are the solutions to lowering methane and co2 emissions?
- carbon capture and storage (co2 absorbed into porous rocks like limestone)
- eat less meat (fields for animals can be used for plants)
What are the two impurities of hydrocarbons?
- nitrogen oxide, sulphur dioxide
What is meant by ‘locked up’?
CO2 becomes a carbon compound in plants and decomposed into fossil fuels and sedimentary rocks
What are examples of renewable energy sources
- wind
- soar
- nuclear
How can manufacturing processes be more efficient
Use less energy, produce less waste
How can you calculate carbon footprint?
Take into account:
- how raw materials are sourced
- manufacturing process
- transportation
- total amount of power used in its lifetime
- how disposed of
What is a carbon footprint?
The total amount of CO2 and greenhouse gases emitted over something’s lifetime
What are the benefits of a carbon footprint?
- determines how eco damaging a product is (is it worth it)
- identify the most polluting activities
What is thermal decomposition?
A reaction when a compound is broken down into a simpler substance when heated
What is the equation for thermal decomposition with calcium carbonate
CaCO3=CaO+CO2
What is cracking?
Breaking down long chain hydrocarbons into short chain hydrocarbons by thermal decompositon
Why do we crack long chain hydrocarbons?
Highest demand is for short chain hydrocarbons
What are the problems with long chain hydrocarbons
- difficult to ignite
- burns incompletely (produces soot)
What are the two methods of cracking?
Steam cracking and catalytic cracking
What is the process of catalytic cracking?
- hot (500’c) powdered aluminium oxide (catylist)
- pass vapourised long chain hydrocarbon over powder
- eventually long chain splits
What is the process of steam cracking?
- mix vapourised long chain hydrocarbon with steam
- heat to a very high temperature (450-700)
What are polymers
Long chain molecules made from short chain monomers
Why do polymers have high melting points even though they have covalent bonds?
They are simple molecular substances
What are the order of fractions in fractional distilition (top to bottom_)
- refinery gases
- petrol
- naphtha
- kerosine
- diesel
- lubricating oil
- fuel oil
- bitumen residue
