Organic questions Flashcards
Simple 1 marker organic questions
Alkene is mixed with bromine water (Br2).
What is the colour change?
Brown/yellow/orange becomes colourless.
Carbon-carbon double bond reactions with Br-Br in addition reaction.
Which has higher boiling point?
a) straight-chain hydrocarbon
b) branched hydrocarbon
a) straight-chain hydrocarbon
Branched hydrocarbons do not fit neatly together.
Straight-chains have more surface area interaction between each molecule allowing more induced dipole-dipole attraction.
Define:
a) Complete combustion
b) Incomplete conbustion
Complete combustion is oxidising a fuel in excess oxygen. This forms H2O + CO2
Incomplete conbustion is oxidising a fuel in limited oxygen. This forms soot (carbon) + CO (carbon monoxide) + H2O
What are the 3 stages of Free-radical substitution?
Initiation
Propagation
Termination
Define electrophilic…
a) substitution
b) addition
a) When an electrophile attracts pair of electron forming covalent bond from the hydrocarbon (usually aromatic ring eg. benzene) replacing a molecule (usually hydrogen ion) in the process.
b) When an electrophile attracts pair of electron from double carbon-carbon bonds forming covalent bond in the process. No molecules come off the hydrocarbon.
As the carbocations have more alkyl (R) groups attached, they become…
a) more stable
b) less stable
a) more stable
Define…
a) biodegradable
b) bioplastic
a) When a material is affected by the environmental conditions leading to decomposition.
b) A material made from renewable source that is biodegradeable.
What is the difference between primary, secondary and tertiary alcohols?
They contain different amounts of alkyl (R) groups on the carbon bonded to the hydroxyl (-OH) group.
Primary: 1 R group - can be oxidised into aldehyde
Secondary: 2 R group - can be oxidised into ketone
Teriary: 3 R group - cannot oxidise
What are nucleophiles?
They are molecules that donate pair electrons to form covalent bonds. They are also know as Lewis bases.
Explain the trend
- The strength of the bond decrease going down the halogen group.
- Atomic radius increases down the group.
- More electron shielding.
- Going down the group, the mean bond enthalpy decreases.
How are Rf values worked out?
Rf = (distance travelled by spot)/(distance travelled by solvent)
A chiral carbon has…
4 different groups attached to it.
Optical isomers are molecules which are…
non-superimposable mirror images of each other. They have the same chemical properties but interact with polarised light differently.
