Alkanes Flashcards
Are alkanes a saturated or unsaturated hydrocarbon?
Saturated hydrocarbon
What makes a saturated hydrocarbon?
They contain only carbon-carbon and carbon-hydrogen single bonds.
What is the main source for alkanes?
Crude oil
What are alkanes used for?
Fuel and lubricants
What is the general formula for an alkane?
CnH2n+2
What is another name for unbranched chains of hydrocarbons?
straight chains
At what angle is the carbon-carbon bonds on a straight chain alkane?
109.5* (so the chains are not actually straight)
What are the three different forms of alkanes?
straight chains
branched chains
ring alkanes
What is the general formula for a ring alkane?
CnH2n (because there are no end hydrogens because it is a circle)
What is the suffix for an alkane?
-ane
How do you find the root name when naming alkanes?
You look for the longest unbranched chain. For example,
How many isomers does butane have?
2
How many isomers does pentane have?
3
How many isomers does hexane have
5
How many isomers does heptane have?
9
How many isomers does octane have?
18
Why are alkanes almost non-polar?
Because the electronegativities of carbon and hydrogen are so similar
What are the only intermolecular forces between their molecules?
weak van der Waals forces.
The larger the molecules the stronger or weaker the van der Waal forces will be?
the stronger
As the chains of the alkanes increase does the boiling point also increase or decrease?
increase
Why do alkanes with branched chains have a lower melting point than there non-branched chained siblings?
They can not pack together as closely as unbranched chains and so the van der Waals forces are not so affective
Are alkanes soluble or insoluble in water?
Alkanes are insoluble in water
Why are alkanes insoluble in water?
because water molecules are held together by hydrogen bonds which are much stronger than the van der Waal’s forces that act between alkane molecules
When alkanes burn with plentiful supply of oxygen what do they produce?
Carbon dioxide and water (CO2 + H2O)
When alkanes burn with a restricted supply of oxygen what do they produce?
carbon monoxide (or carbon) and water (CO + H2O)
What will alkanes react with under suitable conditions?
The halogens
