Q12.41P - Chemistry: Molecular Nature Of Matter And Change

Question

Which member of each pair of compounds forms intermolecular H bonds? Draw the H-bonded structures in each case:

(a)  ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CHOHCH}}_{\mathbf{3}}$ Or  ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{SCH}}_{\mathbf{3}}$    (b)  $\mathbf{HF}$ or  $\mathbf{HBr}$

Step-by-Step Solution

Answer

1. ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CHOHCH}}_{\mathbf{3}}$or ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{SCH}}_{\mathbf{3}}$ : The H-bonding exist in  ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CHOHCH}}_{\mathbf{3}}$molecule as O-atom is more electronegative than S-atom. As O-atom is smaller in size than S-atom
2.  $\mathbf{HF}$or  $\mathbf{HBr}$: $\mathbf{HF}$ molecule shows Hydrogen bonding as the F-atom is more electronegative than Br-atom. Due to its small size, the F-atom electron are closer to the nucleus.

Step 1: Intermolecular Forces

Intermolecular forces are the interaction which are formed by the attraction of the two having opposite charges (partial positive and partial negative charge). The opposite charge are formed by the presence of the electron-negative atom in the molecule. Due to the presence of an electron-negative atom, there is an induced partial positive charge is generated on the electron-positive charge (or less electron-negative charge) atom. There will be an attraction between the both oppositely charges to form a bond.

 

Hydrogen bonding: These types of interactions are present in the electropositive and electronegative atom. There are the interaction between the opposite charge atom which are induced by the presence of the electronegative atom.0

 

Step 2: Inter-particle interaction Explanation

The inter-particle interaction is a type of attraction between the atoms in the molecule. 

 

a.  ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CHOHCH}}_{\mathbf{3}}$or${\mathbf{CH}}_{\mathbf{3}}{\mathbf{SCH}}_{\mathbf{3}}$  : The molecule ${\mathbf{CH}}_{\mathbf{3}}{\mathbf{CHOHCH}}_{\mathbf{3}}$ shows hydrogen bonding between both of them. The reason behind this is that O-atom is a more electronegative atom S-atom because of the smaller size of the O-atom. A hydrogen bond is the bond between the electronegative atom and the electropositive atom. There is less difference in the electronegativity of S-atom and C-atom.

 

b.  $\mathbf{HF}$or $\mathbf{HBr}$ : The molecule  $\mathbf{HF}$ shows hydrogen bonding which is called weak van der Waal's bond. The reason behind this is that F-atom is more electronegative than Br-atom because of the smaller size of F-atom. The valence electron is closer to the nucleus in F-atom than in Br-atom. The hydrogen bond is the bond between the electronegative atom and the electropositive atom. There is less difference in the electronegativity of H-atom and Br-atom.