Chemistry 7.1.4 Flashcards
Alkanes are ___, and Alkenes are ___.
Saturated, Unsaturated.
What Process is used to convert Long Chain Alkane Molecules into Short Chain Alkane Molecules?
Cracking.
Why are Long Chain Alkane Molecules further processed to produce shorter chains?
Because they are more useful.
What is Produced from Cracking?
Small Alkenes & Hydrogen.
What are the 2 types of Cracking?
-Steam Cracking.
-Catalytic Cracking.
Explain the Process of Catalytic Cracking: (5)
-Heat the Hydrocarbon Molecules to ~470-550’C to Vaporise them.
-Vapours pass over a hot powdered Catalyst of Aluminium Oxide.
-Covalent Bonds in the Molecules are broken, as they come into contact with the Catalyst. Thermal Decomposition Reactions.
-Mixture of smaller Alkanes & Alkenes is produced.
-Hydrogen and a higher proportion of Alkenes are formed at higher Temperatures and higher Pressure.
Explain the process of Steam Cracking: (2)
-Vaporised Hydrocarbons are mixed with steam.
-Heated to a high Temp., which induces Cracking.
Define ‘Alkenes’:
Alkenes are a Homologous series of Hydrocarbon Compounds with at least one Double Bond between two of the Carbon Atoms in the Chain.
Double Bond between Carbon Atoms would be written as:
C=C
The General Formula for Alkenes:
CnH2n
Why are Alkenes generally more desirable than Alkanes?
Because they are more Reactive.
Why are Alkenes more Reactive than Alkanes?
Because of the C=C Double Bond. So they can take part in Reactions in which Alkanes cannot.
What is an ‘Addition Reaction’?
A Reaction where the Molecule Chains are ‘added’ up, so all Molecules in the Equation are satisfied, with the correct number of Bonds.
The presence of the C=C Double Bond in Alkenes allows them to ___ in ways that Alkanes cannot.
React.
How can we tell Alkanes & Alkenes apart?
The Bromine Water Test.
