Organic chemistry Flashcards
What is crude oil
A mixture of many different carbon compounds
What are Alkanes
-saturated hydrocarbons
-All the carbon-carbon bonds are single covalent bonds
-They contain as many hydrogen atoms as possible in each molecule
What are the 4 alkanes
What is general formula for Alkanes
Crude oil is separated into …
-Fractions using fractional distillation
-The properties of each fraction depend on the size of the hydrocarbon molecules in it
Lighter fractions make better ..
-Fuels as they ignite more easily and burn well with cleaner flames
What are the properties of short chain hydrocarbons
-low boiling point
-higher volatility
-low viscosity
-higher flammability
What are the properties of long chain hydrocarbons
-high boiling point
-low volatility
-high viscosity
-low flammability
When hydrocarbons burn in plenty of air they …
Transfer lots of energy to the surroundings
What is complete combustion
When a hydrocarbon burns with a rich supply of oxygen
What does complete combustion produce
-carbon dioxide
-water
What is incomplete combustion
When a hydrocarbon burns with a limited supply of oxygen
What does incomplete combustion produce
-carbon dioxide
-carbon monoxide
-carbon(soot)
What are 3 tests for gases formed in complete combustion
-carbon dioxide turns limewater cloudy
-water turns blue copper chloride pink
-oxygen relight a splint
In complete combustion carbon and hydrogen are ..
Oxidised completely when they burn like this
What is cracking
-a heavy fraction distilled from crude oil is heated to vaporise the hydrocarbons
-the vapour is then either passed over a hot catalyst or mixed with steam and heated to a very high temperature
-the hydrocarbons are cracked as thermal decomposition reactions take place
-the large molecules split apart to form smaller, more useful ones
What are Alkenes
-unsaturated hydrocarbons
-contain at least one double bond between their carbon atoms
-as carbon atoms form four covalent bonds it means that alkenes have two fewer hydrogen atoms in their molecules than alkanes
Alkenes are more reactive than …
Alkanes
What is the test for Alkenes
-alkenes react with orange bromine water
-if alkenes are present the orange bromine water will turn colourless
-alkanes do not react with bromine water
What are the properties of alkenes
-burn in air(but not as well as small alkanes)
-react with bromine water, decolourising it
