Chemistry- Organic Chemistry Flashcards
(38 cards)
Define Homologous series
Family of chemicals with the same functional group or general formula
What is the difference between alkanes and alkenes?
Alkane:
- CnH2n+2
- Saturated hydrocarbons
- Single carbon bond (sigma bond)
Alkene:
- CnH2n
- Unsaturated hydrocarbon
- Double carbon bond (pi Bond)
What are the main products produced by thermal cracking?
High percentage of small alkenes such as Ethene
Also forms one or more small alkanes and one alkene molecule (naptha)
What are the conditions used during thermal cracking?
- Very high temperatures (400-900 degrees)
- High pressure (70 atmospheres = 7000KPa)
- No catalsyt
What are the conditions used during catalytic cracking?
- High temperature (450 degrees)
- Slight pressure (1 atmosphere)
- A ZEOLITE catalyst is also used which is silicon dioxide + aluminium oxide in a honeycomb structure to increase Surface Area
What are the products produced from catalytic cracking?
- Branched Alkanes (fuels)
- Cycloalkanes (fuels)
- 2-methlyheptane (petrol)
- Aromatic hydrocarbons
What is Isomerism?
2 or more compounds have the same molecular formula but different arrangement of atoms.
Isomers may have different physical and chemical properties (dependant on the type of isomerism)
What are the 2 main types of isomerism?
What kind of Isomers come under each type?
structural isomers -Chain
- Positional
-Functional group
Sterioisomerism - Geometrical
- Optical
What are general structural isomers?
Have the same molecular formula but their structural formulas are different.
What is chain isomerism?
Same molecular formula and functional group but their arrangement of the carbon atoms in the chain are different.
What are positional isomers?
Same molecular formula and functional group but the position of the functional group is different.
What are functional group isomers?
Same molecular formula but their functional group is different.
Eg. CH3CH2CH2CHO Butanal
Eg. CH3CH2COCH3 Butanone
What are geometric isomers?
Have the same structural formula but the bonds are arranged differently in space.
Geometric isomers often occur with a double bond.
When do geometric isomers occur?
When there is a double bond between 2 carbon atoms which have 2 different groups on them resulting in E and Z isomers.
How do you name geometric isomers?
If two atoms with the greatest atomic numbers are on the same side of the double bond it is a Z isomer. If they are on opposite sides then it is an E isomer.
E (trans) = Opposite side of c=c double bond
Z (cis) = Same side of c=c double bond.
What is an electrophile?
An atom which is electron deficient and therefore is attracted towards an electron dense area of another molecule during an organic reaction.
An electron pair acceptor
How can alkanes (unreactive) be attacked?
By very reactive free radicals.
What is a Haloalkane?
A group of chemical compounds derived from alkanes with one or more halogens bonded to them.
What mechanism do you use to show the formation of haloalkanes?
Free radical substitution.
What are the steps in doing a free radical substitution mechanism?
1) Initiation
2) Propergation
3) Termination
This reaction is a chain reaction process.
What is Ozone and what is its structure?
O3 but there is a dative covalent bond within the structure resonating between the 3 oxygen molecules.
Why is the Ozone layer important to the earth?
Ozone filters out harmful UV radiation from the sun.
What were CFC’s used for? (chloroflourocarbons)
Refrigerants
aerosols
What is the problem with having CFC’s in the atmosphere?
UV light can break the C-Cl bonds creating free radicals of .Cl Which may react with with the O3 causing a chain reaction and a constant overall reaction of 2O3 —–> 3O2.
