C7 Organic Chemsitry Flashcards
What is catalytic cracking?
At high temperatures
Hydrocarbons are vapourised
Pass over an aluminum oxide catalyst
What is steam cracking?
High temperatures
Hydrocarbons are vaporised
Vapours mixed with steam
What and how is crude oil made?
A mixture of the compounds of hydrocarbons which is made when ancient biomass -mainly plankton- is buried in mud. Finite resource
What id the formula for the alkanes?
CnH2n+2
What are the first four alkanes with the formula?
Methane-CH4
Ethane-C2H6
Propane-C3H8
Butane-C4H10
Describe the process of fractional distillation
Hydrocarbons have different boiling points, crude oil enters the column and is heated to a vapour.The column has a temperature gradient, the short chain molecules have low boiling points so condense at the top of the column. Whereas long chain hydrocarbons have high melting point so condense at the bottom.
As the size of hydrocarbons increases, what happens to the properties:
Flammability, boiling point and viscosity?
Flammability decreases
Boiling point increases
Viscosity increases
What does the combustion of hydrocarbons release?
Releases energy and means the carbon and hydrogen fuels are oxidised.
Releases carbon dioxide and water
ALKANE+Oxygen—>Carbon dioxide+Water
What is the chemical test and color change for the Alkenes?
Bromine water
Orange—> colorless
What is cracking? And equation
The thermal decomposition of long chain hydrocarbon molecules into shorter, useful hydrocarbon molecules.
Long chain molecules—Heat—> small chain alkane + alkene ( with carbon double bond)
Products of cracking:
What are the uses of short chain alkanes and alkenes
Short chain alkanes: fuels-petrol/diesel
Alkenes:Chemical feed stocks such as playoffs and medicines
What is the formula for the Alkenes?
CnH2n
What are the products of cracking and their uses?
-Short chain hydrocarbons: fuels such as petrol and diesel
-Alkenes:Plastics and medicines
What does the incomplete combustion of hydrocarbons release?
ALKENE+oxygen—>Carbon+Carbon monoxide+Carbon dioxide+water
Similarities and differences between alkanes and Alkenes
-Alkenes:Double carbon to carbon bond ,unsaturated-less hydrogen atoms,Decolourises bromine
-Alkanes:Single bonds, Saturated-full quantity of hydrogen atoms
-Both:Combust in oxygen, covalent bonding, molecular structure
