Saved Bookmarks
| 1. |
Which of the following statement is/are correct? |
|
Answer» The conjugate acid of `NH_(2^((-)))` is `NH_(3)` `K_(a)` values decrease successively since it is difficult to remove `H^(o+)` ion from an anion thatn a netural compound. Similarly, it is difficult to remove `H^(o+)` ion from an dianion than an anion. HENCE `K_(a_(1)) gt K_(a_(2)) gt K_(a_(3))` B. Statement B is incorrect. `H_(3)PO_(4) overset(K_(a_(1)))hArrH^(o+)+H_(2)PO_(4^(T))` `H_(2)PO_(4^(T))overset(K_(a_(2)))hArrH^(o+) + HPO_(4^(2-))` `pH(H_(2)PO_(4^(T))) = (pK_(a_(1)) + pK_(a_(2)))/(2)` This is valid only when `H_(3)PO_(4)` during titrating is completely CONVERTED to `H_(3)PO_(4)^(T)`. `HPO_(4^(2-)) overset(K_(a_(2)))hArrH^(o+) + PO_(4^(3-))` `pH(HPO_(4)^(2-))= (pKa_(2) + pKa_(3))/(2)` This is again valid when starting with `H_(2)PO_(4)^(2-)` and is completely converted to `HPO_(4)^(2-)` C. Statement C is correct From the `K_(a)` values it is evident that both `H_(3)PO_(4)` and `H_(2)PO_(4^(T))` are more acidic than `HPO_(4^(2-))` Statement D is incorrect. Both `H_(2)PO_(4^(T))` and `HPO_(4^(2-))` are amphoprotic anion in the solution. `H_(3)PO_(4)overset(+H^(o+))larrH_(2)PO_(4^(T))overset(-H^(o+))rarrHPO_(4)^(2-)+H^(o+)` `H_(2)PO_(4^(T)) overset(+H^(o+))larrHPO_(4)^(2-)overset(-H^(o+))rarrPO_(4^(3-))+H^(o+)` |
|