Login/Sign Up
Home » Arrange the following in the order of property indicated for each set:(i) F2, Cl2, Br2, I2 – increasing bond dissociation enthalpy.(ii) HF, HCl, HBr, HI – increasing acid strength.(iii) NH3, PH3, AsH3, SbH3, BiH3 – increasing base strength.
Arrange the following in the order of property indicated for each set:
(i) F2, Cl2, Br2, I2 – increasing bond dissociation enthalpy.
(ii) HF, HCl, HBr, HI – increasing acid strength.
(iii) NH3, PH3, AsH3, SbH3, BiH3 – increasing base strength.
CBSE | Chemistry | Class 12 | NCERT | The p-Block Elements
Arrange the following in the order of property indicated for each set:
(i) F2, Cl2, Br2, I2 – increasing bond dissociation enthalpy.
(ii) HF, HCl, HBr, HI – increasing acid strength.
(iii) NH3, PH3, AsH3, SbH3, BiH3 – increasing base strength.

(1) Bond dissociation energy normally decreases while moving down a group because of the increase in the atomic size. However, F2 has a lower bond dissociation energy than Cl2 and Br2 because of the smaller atomic size of fluorine.
Hence, the increasing order for bond dissociation enthalpy is as follows:
I2< F2< Br2< Cl2
(2)  Bond dissociation energy of  a H-X molecule ( where X = F, Cl, Br, I ) decreases with an increase in the size of an atom. As H-I bond is the weakest, it will act as the strongest acid.
Therefore, the increasing order acidic strength is as follows:
HF <HCl<HBr< HI

(3) BiH3≤ SbH3<AsH3< PH3< NH3
On moving down a group from nitrogen to bismuth, the atomic size increases but the electron density of the atom decreases (rapid increase in the volume of atoms). Hence, the basic strength decreases.

i

More Material