Question 10.2:
Why is sulphuric acid not used during the reaction of alcohols with KI?
Answer:
In the presence of sulphuric acid (H2SO4), KI produces HI
Since
is an oxidizing agent, it oxidizes HI (produced in the reaction to I2).
As a result, the reaction between alcohol and HI to produce alkyl iodide cannot occur. Therefore, sulphuric acid is not used during the reaction of alcohols with KI. Instead, a non-oxidizing acid such as H3PO4 is used.
Question 10.3:
Write structures of different dihalogen derivatives of propane.
Answer:
There are four different dihalogen derivatives of propane. The structures of these derivatives are shown below.
(i)
1, 1-Dibromopropane
(ii)
2, 2-Dibromopropane
(iii)
1, 2-Dibromopropane
(iv)
1, 3-Dibromopropane
Question 10.4:
Among the isomeric alkanes of molecular formula C5H12, identify the one that on photochemical chlorination yields
(i) A single monochloride.
(ii) Three isomeric monochlorides.
(iii) Four isomeric monochlorides.
Answer:
(i) To have a single monochloride, there should be only one type of H-atom in the isomer of the alkane of the molecular formula C5H12. This is because, replacement of any H-atom leads to the formation of the same product. The isomer is neopentane.
Neopentane
(ii) To have three isomeric monochlorides, the isomer of the alkane of the molecular formula C5H12 should contain three different types of H-atoms.
Therefore, the isomer is n-pentane. It can be observed that there are three types of H atoms labelled as a, b and c in n-pentane.
(iii) To have four isomeric monochlorides, the isomer of the alkane of the molecular formula C5H12 should contain four different types of H-atoms. Therefore, the isomer is 2-methylbutane. It can be observed that there are four types of H-atoms labelled as a, b, c, and d in 2-methylbutane.
Question 10.5:
Draw the structures of major monohalo products in each of the following reactions:
(i)
(ii)
(iii)
(iv)
(v)
(vi)
Answer:
(i)
(ii)
(iii)
(iv)
(v)
(vi)