Unit 2 - Hydrocarbons/Homologous series Flashcards
What is a fuel?
Material such as coal,gas or oil that is burned to produce energy
What is fractional distillation
Separation technique to separates a mixture into a number of different parts, called fractions. A tall fractionating column is fitted above the mixture, with several condensers coming off at different heights. The column is hot at the bottom and cool at the top.
What is combustion?
Combustion = burning.
When hydrocarbons are burned, they react with O2 to produce H2O and CO2
Why do we use fuels?
For energy
What is the chemical term for burning?
Combustion
What are hydrocarbons made up of?
Hydrogen and carbon atoms
Definition of a homologous serie.
A family of compounds which have the same general formula and similar chemical properties.
Describe the structure of alkanes
Homologous series of hydrocarbons
All carbon to carbon bonds are single covalent bonds
Names all end in -ane
What is the general formula for alkane?
CnH2n+2
General formula for cycloalkanes and Alkenes
CnH2n
Describe cycloalkanes
Starts with cyclo and end in -ane
They form a sort of cirlce.
Are saturated so are carbon to carbon single covalent bonds.
Describe alkenes
Names all end in -ene
All alkenes are unsaturated (double bond)
Contain at least 1 carbon to carbon double bond
How to name Alkanes
- Find the longest carbons chain and name it (using prefixes and ending in -ane).
- Name any chain (count the number of carbon in the chail, use the prefix and add -yle at the end).
- Determine the position of the branched
Longest chain of carbons and name if using prefixes and add -ane at the end number the carbons do it the direction that will make the branch a low number Name what carbon the branch is on Use di for 2 branches, tri for 3 If two branches are coming off each other use ethane
How to name Alkenes
- find the longest chain of carbons containing double bond and name it using prefixes and add -ene at the end
- Number the double bond making sure it’s in the direction to get a small number
- Add this number between the prefix and -ene
e. g: Pent-2-ene
What prefixes don’t exists in alkenes
Meth
You cannot have double bond if you only have one carbon
what are Alkanes used for?
Fuels
What are Cycloalkane used for?
used as a solvent
What are alkenes used for?
Polymers and making alcohols
What is the test for unsaturation?
Unsaturation (=double bond)
Test: using bromine water (an orange/brown solution)
Result: Bromine water decolourised in the presence of unsaturation (double bonds)
Alkenes can udergo addition reaction.
What is the name of the addition reaction when Bromine is added to an alkenes?
Bromination or dihalogenation
Forming a dihaloalkanes.
Alkenes undergo addition reaction with hydrogen, what is the name is this particular addition reaction?
What are the product called?
- name of reaction: Hydrogenation
- Products formes: alkanes
Alkenes undergo addition reaction with water.
What is the name of this addition reaction, and what are the product formed?
Addition reaction with water is called: hydration
Forming alcohols
Write the a chemical balanced equation for the combustion of 3-methyloctane.
C9H20 + 14O2 –> 10H2O + 9CO2
What are the products for complete combustion of a hydrocarbon?
Water and carbon dioxide.
What are the products for incomplete combustion of a hydrocarbon?
Water and carbon monoxide
Is combustion an endothermcic or exothermic reaction?
exothermic as it produces heat.
What prefixes don’t exist with cycloalkanes?
meth and eth
(you need at least 3 carbons to form a cycle)
Definition of isomers
molecules with the same chemical formula but different structural formula.
hept-3-ene
