SC9 - Organic Chemistry Flashcards
What are hydrocarbons?
Molecular compounds which contain only carbon and hydrogen atoms.
What are alkanes?
Alkanes are a group of hydrocarbons which are based on a chain of carbon atoms. They are saturated (no double covalent bonds). They are in the same homologous series.
E.g. Ethane
H H I I
H-C-C-H
I I
H H
What is a homologous series?
A group of chemicals which have the same general formula, similar chemical properties and show a trend in physical properties.
What is the general formula for alkanes?
CnH2n+2
What are the prefixes for the first 4 hydrocarbons?
Meth- (1 carbon)
Eth- (2 carbons)
Prop- (3 carbons)
But- (4 carbons)
What are alkenes?
Unsaturated hydrocarbons (contain a double covalent bond between carbon atoms).
E.g. Ethene
H H
I I
C=C
I I
H H
What is the general formula for alkenes?
CnH2n
What is a functional group?
The atom or group of atoms which are mainly responsible for a molecule’s chemical properties.
What is the functional group for alkenes?
C=C
What is the functional group for alkanes?
C-C
What is an isomer?
An isomer is a molecule with the same molecular formula but different arrangements of atoms (e.g. but-1-ene has the C=C bond first, but-2-ene has the C=C bond second)
What is formed during the complete combustion of hydrocarbons?
Carbon dioxide and water only
E,g. Methane + oxygen —> carbon dioxide + water
What is formed during the incomplete combustion of a hydrocarbon?
Particulate carbon (soot) may form as well as or instead of water and carbon dioxide.
What is the test for alkenes?
Bromine water is an orange-brown colour. When it is mixed with alkenes a chemical reaction occurs, leading to colourless products. Alkanes do nit cause this decolourisation.
What happens during the reaction of ethene and bromine water?
This is an addition reaction (the carbon double bond opens up and forms a structure like an alkane with the bromine in it)
ethene + bromine —> 1,2-dibromoethane
H H H H
I I I I
C=C + Br2 —> H-C-C-H
I I I I
H H Br Br
The 1,2 means that the two bromine atoms are attached to different carbon atoms (the first bromine is attached to the first carbon, the second bromine is attached to the second carbon.