P Block Elements

7.9

Generally, in CCl₄, all the C-Cl bonds are equal. But that is not in the case of PCl₅. All the bonds in PCl₅ are not similar. It has three equatorial and two axial bonds. Therefore, when PCl₅ is heated strongly, the axial bonds breakdown and thus PCl₅ decomposes to PCl₃.

7.8

White phosphorous when heated with concentrated NaOH solution (in a CO₂ atmosphere) gives phosphine, PH₃. Another product is Sodium hypophosphite, NaH₂PO₂.

7.6 Diagram of N₂O₅:

Covalence of nitrogen in N₂O₅ is 4 (as can be said from the above diagram).

Note: Covalence is the number of electron pairs that an atom can share with other atoms.

7.5

Ammonia on reacting with Cu²⁺ acts as a Lewis base and donates its electron pair to the metal ion and forms a linkage with the metal ion.

Here, colour of Cu²⁺ is blue whereas the colour of [Cu (NH₃)₄]²⁺ is deep blue.

7.4

Ammonia (NH₃) is generally prepared through a many numbers of processes out of which Haber's process is the most important one. Following the Le Chatlier's principle and taking into considerations the reaction conditions of the Haber's process, the yield of ammonia can be maximized by

High pressure (~ 200 atm)

High temperature (~ 700K)

A mixture of Iron oxide with small amounts of K₂O and Al₂O₃ used as a catalyst. (This mixture acts as a positive catalyst in the Haber's process)

7.3

N₂ (Dinitrogen) is formed by sharing three electron pairs between two nitrogen atoms, which are joined by a triple bond as shown below:

Due to a complete octet of the nitrogen atoms and bonded by strong triple bonds, due to which its bond dissociation energy is very high. Due to this reason, N₂ is very less reactive at room temperature.

7.2

Atomic size increases down the group and thus the stability of the hydrides of Group-15 elements decreases. Now, the least stable hydride is the one which is more reactive and possessing higher reducing strength.

The reducing character of hydrides increases on moving from NH₃ to BiH₃. Hence, BiH₃ is the strongest reducing agent among hydrides of Group-15 elements.

7.1

Pentahalides (like MX5) means the compounds in which metal is bonded with five halogen atoms. Thus, the oxidation state of metal here is +5. Similarly, trihalides (like MX3) means the compounds in which metal is bonded with three halogen atoms.

Thus, the oxidation state of metal here is +3. Now, as the polarizing power is directly proportional to the charge, the metals with the higher charge will have higher polarizing power. Hence, Pentahalides are more covalent than trihalides.
Note: Polarizing power is the ability of a cation to distort an anion.