[Ti(H_(2)O)_(6)]^(+3) gives violet coloured aqueous solution but [Mg(H_(2)O)_(6)]^(+2) solution is colourless, why? (b) At 10^(@) C, the osmotic pressure of urea is 500 mm. The solution is diluted and the temperature is raised to 25^(@) C, when the osmotic pressure is found to be 105.3 mm. Determine the extent of dilution.

[Ti(H_(2)O)_(6)]^(+3) gives violet coloured aqueous solution but [Mg(H

1.	[Ti(H_(2)O)_(6)]^(+3) gives violet coloured aqueous solution but [Mg(H_(2)O)_(6)]^(+2) solution is colourless, why? (b) At 10^(@) C, the osmotic pressure of urea is 500 mm. The solution is diluted and the temperature is raised to 25^(@) C, when the osmotic pressure is found to be 105.3 mm. Determine the extent of dilution.
Answer» Solution :(a) In `[T(H_(2)O)_(6)]^(+3)`, the `d^(1)` electrons occupies `t_(2g)` orbital in octahedral field. On irradiation with light. The `I_(2g)` electron is promoted to `e_(g)` orbital and the resulting absorption band gives violet colour. In case of `[Mg(H_(2)O)_(6)]^(+3)`, the electrons configuration of `Mg^(+2)` is `1s^(2)2s^(2)2p^(6)` which does not permit any electronic TRANSITION `(2p to 3s)` as the energy gap is very LARGE or there does not d-d transition of electrons. Hence, it gives colourles solution. (b) For original solution, `500/700 xx V_(1) = x/m xx S xx 283`..........(1) After dilution, `105.3/760 xx V_(2) = x/m xx S xx 298` ..............(2) Dividing EQUATION (2) by (1) `therefore V_(2)/V_(1) =5` `rArr` The solution is diluted to the extent that `V_(2)` is five times the original VOLUME (V).