benzene 💍

Question 1

what is the molecular formula of benzene

Answer 1

C6H6

Question 2

name the 3 problems with Kekule’s structure

Answer 2

1. Bromine solution did not turn colourless so no addition reaction
2. the carbon - carbon bond lengths are identical
3. the enthalpy of hydrogenation value is less exothermic than expected

Question 3

what was the expected value of enthalpy of hydrogenation and the actual value?

Answer 3

exothermic reaction
expected= -360kjmol
actual= -208 kjmol

Question 4

why does benzene have identical carbon- carbon lengths

Answer 4

because p orbitals overlap its neighbouring p orbitals by the same amount above and below the ring. - the pi cloud

Question 5

why does benzene not undergo an addition reaction with bromine

Answer 5

due to its low electron density

Question 6

why is the enthalpy of hydrogenation value less exothermic than expected

Answer 6

because benzenes delocalised electrons increases its stability

Question 7

explain the bonding in benzene

Answer 7

1. p orbitals overlap above and below the ring to form a pi system
2. p orbitals are delocalised
3. benzene is planar and bond angle is 120

Question 8

naming it benzene

Answer 8

only if the groups are
- halogenoalkane
alkane
nitro (NO2)

Question 9

Naming it phenyl

Answer 9

if carboxylic acid , nitrile , aldehyde, ketone , alcohol

Question 10

benzene test

Answer 10

benzene burns with oxygen producing a smoky flame

Question 11

benzene and incomplete combustion

Answer 11

incomplete combustion . production of carbon particulates