Question

Explain the following giving reasons:
(a) H,PO, is diprotic.
(b) Nitrogen is an exothermic compound but
NCI, is an endothermic compound.
(e) (SiH3)2N is a weaker base than (CH3)2N
why ?

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Answer 1

Two common examples are carbonic acid (H2CO3, which has two acidic protons and is therefore a diprotic acid) and phosphoric acid (H3PO4, which has three acidic protons and is therefore a triprotic acid).

NCl3 is endothermic compound because of its high enthalpy of formation due to large difference in sizes of N and Cl atoms. This large difference makes N-Cl bond weak, while in NF3 the sizes of atoms are not so different, therefore N-F bond is strong and thus it is an exothermic compound.