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p-block elements form acidic, basic and amphoteric oxides. Explanin each property by giving two examples, and also write the reactions of these oxides with water. |
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Answer» i) 2nd period `B_(2)O_(3) lt CO_(2) lt N_(2)O_(3)` acidic nature in increases. ii) 3rd period `Al_(2)O_(3) lt SiO_(2) lt P_(4)O_(10) lt SO_(3)ltCl_(2)O_(7)` Acidic character increases. On MOVING down the group, acidic character decreases and basic character increases, e.g., a) Nature of oxides of 13 group elements.  b) Nature of oxides of 15 group elements. `underset("Strongly acidic")(N_(2)O_(5))` `underset("Moderately acidic")(P_(4)O_(10))` `underset("Amphoteric")(As_(4)O_(10))` `underset("Amphoteric")(Sb_(4)O_(1))``underset("Basic")(Bi_(2)O_(3))` Among the oxides of same element, higher the oxidation state of hte element, stronger is the acid, e.g., `SO_(3)` is a stronger acid than `SO_(2)`. `B_(2)O_(3)` is weakly acidic and on dissolution in water, it forms orthoboric aicd. Orthoboric aicd does not ACT as a PROTONIC acid (it does not ionise) but acts as a weak lewis acid. `underset("Boron trioxide")B_(2)O_(3) + 3H_(2)O ltimplies underset("Orthoboric acid")2H_(3)BO_(3)` `B(OH)_(3) + H- OH to [B(OH)_(4)]^(-)+H^(+)` `Al_(2)O_(3)` is amphoteric in nature. It is insoluble in water but dissolves in alkaklies and reacts with acids. `("Aluminium trioxide")Al_(2)O_(3) + 2NaOH overset(DELTA)to underset("Sodium meta aluminate")2NaAlO_(2) + H_(2)O larr Al_(2)O_(3) + 6HCl overset(Delta)to underset("Aluminium chlroide")2AlCl_(3) + 3H_(2)O` `Ti_(2)O` is an basic as NaOH due to its lower oxidation state `(+1)` `TI_(2)O + 2HCl to 2TICl + H_(2)O` `P_(4)O_(10)` on reaction with water gives orthophosphoric acid. `underset("Phosphorous pentoxide")(P_(4)O_(10)) + 6H_(2)O to underset("Orthophosphoric acid")(4H_(3)PO_(4))` `Cl_(2)O_(7)` is strongly acidic in nature and on dissolution in water, it gives perchloric acid `underset("Dichlorine heptoxide")(Cl_(2)O_(7)) + H_(2)O to underset("Perchloric acid")2HCIO_(4)` |
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