Question

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3) Which one of the following sets of ions shows an order of lowest to highest hydration energy? ) Ca2+ < K+ < Rb+ B) Ca2+ < Nat < Mg2+ Lit <kt < Cs b) Mg2+ < Ca2+ < Ba2+ E) Rb* <K* < Ca2+

Answer 1

Ն Ն Ն Ն Ն Ն Ն 3.) HYDRATION ENERGY • Hydration energy is the amount of energy released when a species gets surrounded by water due to electrostatic attraction. This interaction leads to evolution of energy. Hydration intensity depends on the charge density of a species. So, among tuwo ions with same charge, the one with a smaller radius will have more hydration energy Generally, in Groups size increases down the group, the hydration energy decreases down the group. Group 2 ions have hydration enthalpies higher than group s. since group 2 cations are doubly charged and have smaller size order of lowest to highest hydration energy A Cazt <kt < R6* Ca2+ belongs to the group 2 and kt and Rbt belongs to group 1 :. Group 2 ions have hydration energy higher than group 1 ., so this order of highest to lowest so, this option is NOT worect. B) Cezt < Nat Mozt Here, cazt is larger in size than mg 2+ so, ca²1 have low hydration energy than mg et ! But its hydration is higher than Nat because Ca?t belongs to group 2 :. this is also NOT a correct order Ꮓ Ꮓ Ꮓ Ꮓ x (

(C) L+KK+ est hit being smaller in size have highest hydration energy and cst being larger in size ham smallest- hydration energy. Therefore this is not correct order. (D) Mg2tc cast < Baat Mg 2+ being smaller in size have highest hydration energy and Ba²t being larger hame lowest hydration energy. This highest to lowest hydration energy order. Therefore this is also NOT correct order. Rbt being eary coat belongs to LE) Rot (k+ (cast R6t being larger in size have lowest hydration aroup 2 energy haming and higher hydration energy than group 1. Therefore this is lowest to highest hydration energy order. So, this is the CORRECT ORDER group 2 concluding option (E) shows an hydration energy order of lowest to highest