3.2 - Alkanes Flashcards
What are the 3 stages of the mechanism of Halogenation of Alkanes?
|> Initiation
|> Propagation
|> Termination
Name of mechanism: Halogenation of Alkanes
Free-radical Substitution
Define: Propagation (free-radicals)
Formation of Free Radicals
What is produced from catalytic cracking?
|> Cyclic & branched Alkanes
|> Aromatic Rings (e.g. Benzene)
Define: Initiation (free-radicals)
Formation of radicals under UV light
What does Thermal Cracking produce?
|> Alkanes
|> High % of Alkenes
What are the Catalysts used in Catalytic Converters?
Rh, Pd, Pt
As the length of a carbon chain increases, the boiling point ____ ?
Increases
Why are power station chimneys coated with CaO or CaCO₃?
Remove Sulfur Dioxide from Flue Gas
Form Plasterboard
What are the Conditions for Halogenation of Alkanes?
U.V. Light
Why does boiling point decrease as no. of branches increases?
|> Less points of contact
|> VDWs become weaker
|> Less energy to break
What conditions is Thermal Cracking carried out at?
v. High Temp
High Pressure
Why are Alkanes not soluble in Water?
|> They are non-polar
|> Water molecules are held together by hydrogen bonds, which are much stronger than VDWs
What is produced from Further Incomplete combustion of Alkanes?
solid C & H₂O
Define: Structural isomers
Molecules with the same molecular formula but a different structural formula
What are the products of Catalytic Cracking used for?
Motor Fuels
Why does boiling point Increase as Chain Length Increases?
|>More electrons
|>Stronger temporary dipoles
|>More energy needed to break
Define: Saturated Hydrocarbons
Only contain single C-C bonds
Define: Cycloalkane
|> Have general formula CnH₂n
|> Named according to largest ring
What Inter-molecular forces attract neighbouring Alkane molecules?
weak VDWs
As the number of Branches in an Alkane Increases, the boiling point ____ ?
Decreases
What is produced from Incomplete combustion of Alkanes?
CO & H₂O
Are alkanes polar or non-polar?
|> Non-polar
|> C & H have similar electronegativity vaues
Define: Hydrocarbon
Compounds that contain Carbon & Hydrogen atoms only
What is produced from Complete combustion of Alkanes?
CO₂ & H₂O
Define: Free-radical
Species with an Unpaired electron
What type of reaction is Halogenation?
Substitution
H atom replaced by Halogen atom
Define: Chain isomers
Same molecular formula, different longest chain lengths with -yl groups
Why are Alkanes non-polar?
C & H have very similar electronegativity values
Shape and Bond Angle around a C atom?
Tetrahedral
109.5°
What is the general formula for Aliphatic (chain) Alkanes?
CnH₂n₊₂
Why do catalytic converters have a honeycomb structure?
Larger Surface Area
What do Catalytic Converters remove?
CO, NOₓ & unburned hydrocarbons
How is Catalytic Cracking carried out?
High Temperature
Slight Pressure
Zeolite (porous solid) Catalyst
How are Nitrogen Oxides (NOₓ) produced?
N₂ + O₂ & electrical spark
