what is hydration enthalpy...n how does it vary along a period n group????

what is hydration enthalpy...n how does it vary along a period n group????


2 Answers

Anil Pannikar AskiitiansExpert-IITB
85 Points
13 years ago


Dear Shreya,


 Hydration enthalpy is the energy released when 1 mol of a substance is dissolved into a solution. It is always negative, as attraction bonds (e.g. dative, ion-dipole) are being formed. The higher the charge on the ions and the smaller their size, the more exothermic the hydration enthalpy or u can say more negative value. As, atomic size generally decreases from left to right in a period so, Hydration enthalpy is expected to increase i.e. more negative value.


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Askiitians Expert

Anil Pannikar

IIT Bombay

Devasish Bindani
45 Points
13 years ago

when a subs tance is put in water, it gets dissolved. for dissolving the loose bonds or inter mecular forces which hold the molecules together should be broken. since we know that water molecules donot have fixed places like in solids so the molecules posses some energy in them. when a substane is put in water or any liquid the particles collide on it and trans fer the energy. if the energy transferred is enough to break the inter molecular bond then the substance gets dissolved.this energy which is used in dissolving the substance in liquid is known as hydration enthalpy

         it increases from left to right in a period and decreases down the group

note the explaination of hydration enthalpy is just to give an idea how the mechanism or how the process occour it may be correct or wrong please reffer others also all the best for iit preparation

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