Organic Chemistry Flashcards
1
Q
What are hydrocarbons?
A
- molecules that are made up of hydrogen and carbon atoms only
2
Q
What are alkanes?
A
- a hydrocarbon
3
Q
What are the names and displayed formulas of the first five alkanes?
A
- methane: CH4
- ethane: C2H6
- propane: C3H8
- butane: C4H10
- pentane: C5H12
- Mice, Eat, Peanut, Butter, Pentane
4
Q
What is a homologous series?
A
- a group of compounds that can all be represented by the same formula
5
Q
What is the formula for all alkanes ?
A
- CnH(2n+2)
6
Q
What must a compound be to be an alkane?
A
- a saturate hydrocarbon
- saturated means it contains no double bonds
7
Q
What is complete combustion?
A
- when there is plenty of oxygen about, alkanes burn to produce carbon dioxide and water: alkane + oxygen = carbon dioxide + water (+energy)
- it releases a lot of energy and only produces two harmless waste products. gas burns with a clean blue flame
8
Q
What is incomplete combustion?
A
- when there isn’t enough oxygen, alkane combustion will be incomplete
- carbon dioxide and water are still produced, but also get carbon and carbon monoxide
- alkane + oxygen = carbon + carbon monoxide + carbon dioxide + water (+energy)
- produces a smoky yellow flame, and less energy than complete combustion
9
Q
What is a substitution reaction?
A
- chlorine and bromine react with alkanes in the presence of UV light
- a hydrogen atom from the alkane is substituted by chlorine or bromine.
- bromine and methane react together to form bromomethane
10
Q
What are alkenes?
A
- hydrocarbons that have a double bond between two of the carbon atoms in their chain
11
Q
What type of molecules are alkenes?
A
- unsaturated
- they can make more bonds, double bond can open up
12
Q
What are the first four alkenes?
A
- ethene, C2H4
- propene, C3H6
- butene, C4H8
- pentene, C5H10
13
Q
What is the general formula for alkenes?
A
- CnH2n
14
Q
What do halogens react with alkenes to form?
A
- haloakanes
- e.g. bromine and ethene react to form dibromoethane
- these are additional reactions because the C=C bond is split and a halogen atom is added
15
Q
What is the reaction between bromine and alkenes used to test?
- an addition reaction
A
- to test for carbon- carbon double bonds
- when you shake an alkene with orange bromine water, the solution becomes colourless
- this is because the bromine molecules, which are orange, are reacting with the alkene to make dibromoalkane, which is colourless