Section 3 Organic Chemistry Flashcards
What is the general formula for alkanes?
CnH2n+2
Alkanes and alkenes are both ………..
Hydrocarbons
What is complete combustion?
Happens when there’s plenty of oxygen
Produces carbon dioxide, water and lots of energy
What is incomplete combustion?
Happens when there isn’t enough oxygen
Makes carbon, carbon monoxide, carbon dioxide and water
Also produces smokey yellow flame and less energy
Halogens react with alkanes in ……… to make ………
Uv light
Halo alkanes
What do alkenes have?
Carbon double bond
So they are unsaturated molecules (they can make more bonds)
What is the general formula for alkenes?
CnH2n
What do halogens react with alkenes to form?
Haloalkanes
What is the reaction between alkenes and halogens?
Addition reactions
How can ethanol be produced?
Reaction of Ethene and steam
Fermentation
How can ethanol become Ethene?
Dehydration reaction (removing water)
What is the reaction between halogens and alkanes?
Substitution reaction
How can you test for carbon double bonds?
Shake an Alkene with orange bromine water The solution will become colourless Makes dibromoalkane (which is colourless)
Explain how ethanol can be produced from ethene and steam
Reaction needs temp of 300 degrees C Pressure of 60-70 atmospheres Phosphoric acid catalyst Fairly cheap because no Ethene waste Needs crude oil to make ethanol which is non renewable, so will become more expensive
Explain how ethanol can be produced by fermentation?
Sugar e.g. glucose is converted into ethanol using yeast - very slow
Temp of 30 degrees C
Cheap Simple equipment
high labour costs
Uses raw materials that are renewable
Ethanol produced isn’t concentrated so needs to be distilled and purified
How can ethanol be turned back to Ethene?
Dehydration reaction - remove the water
Ethanol vapour is passed over hot catalyst of aluminium oxide Catalyst provides large surface area for reaction
Recall the products of complete and incomplete combustion of alkanes.
Complete (safe): carbon dioxide + water.
Incomplete (not safe): carbon + carbon monoxide + carbon dioxide + water.
Describe the substitution reaction of methane with bromine to form bromomethane in the presence of UV light.
Bromine (halogen) replaces hydrogen atom to form bromomethane (a substitution reaction).
What are the names of the first five alkanes?
Hint: Mice Eat Peanut Butter.
Methane Ethane Propane Butane Pentane
What are the names of the first three alkenes?
Hint: Eggs, Pan, Boil.
Ethene
Propene
Butene.
What is a homologous series?
A group of compounds that can all be represented by the same general formula.
What is a hydrocarbon?
Molecules that are made up of hydrogen and carbon atoms only.
What is a saturated general formula?
Saturated means something has bonded as many times as possible. General formula is the most simplified the ratio of molecules can be.
What is the equation for incomplete combustion?
Alkane + oxygen ➡️ carbon + carbon dioxide + carbon monoxide + water (+ energy)
