Question

Only for mods and brainly stars users , others do not answer !!

Assign reasons for the following :
(i) Copper (I) ion is not known in aqueous solution.
(ii) Actinoids exhibit greater range of oxidation states than lanthanoids. (Delhi 2011)​

Answer 1

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(i) Cu2+(aq) is much more stable than Cu+(aq). This is because although second ionization enthalpy of copper is large but Δhyd (hydration enthalpy) for Cu2+(aq) is much more negative than that for Cu+(aq) and hence it more than compensates for the second ionization enthalpy of copper. Therefore, many copper (I) compounds are unstable in aqueous solution and undergo disproportionation as follows :

2Cu+ → Cu2+ + ᴄᴜ

(ii) Because of very small energy gap between 5f, 6d and 7s subshells all their electrons can take part in bonding and shows variable oxidation states.

ʜᴏᴩᴇ ᴛʜɪꜱ ʜᴇʟᴩꜱ ❤️

Answer 2

Answer:

(i) Cu2+(aq) is much more stable than Cu+(aq). This is because although second ionization enthalpy of copper is large but Δhyd (hydration enthalpy) for Cu2+(aq) is much more negative than that for Cu+(aq) and hence it more than compensates for the second ionization enthalpy of copper. Therefore, many copper (I) compounds are unstable in aqueous solution and undergo disproportionation as follows :

2Cu+ → Cu2+ + Cu

(ii) Because of very small energy gap between 5f, 6d and 7s subshells all their electrons can take part in bonding and shows variable oxidation states.