Question

Select the single best answer. Explain the observed trend in the melting points for four isomers of molecular formula C7H16. mp (°C) CH3CH2CH2CH(CH3)CH2CH3 −119 CH3CH2CH2CH2CH(CH3)2 −118 CH3CH2CH2CH2CH2CH2CH3 −91 (CH3)2CHC(CH3)3 −25

Answer 1

Explanation:

It is known that more linearly the atoms are arranged in a carbon chain more will be its melting point. This is because then more surface area has been occupied by the molecule and in order to break all the bonds, heat energy has to reach to the entire surface area.

As a result, melting point of the compound will be high. On the other hand, more is the branching present in a carbon chain less will be the surface area occupied by it. Hence, smaller will be its melting point.

Therefore, in the given structures of ($C_{7}H_{16}$) as the branching increases there occurs a decrease in melting point.