IIT JEE , AIEEE Forum - Chemistry , Physical Chemistry

liku

Q-The dissolution of NH4Cl in water is endothermic even though NH4Cl dissolves in water spontaneously. Which one of the following best explains this behaviour ?

(a)The bonds in solid NH4Cl are weak.

(b) The entropy driving force causes dissolution.

(c) Endothermic processes are energetically favourable.

(d) The dissolving process is unrelated to energy.

(PLZ EXPLAIN THE ANSWER)

aditya_arora04

Hi liku,

The answer may be as follows :

NH₄Cl does not have weak bonds. It is ionic in nature. Option 1 wrong.

Now NH₄Cl when dissolves, 1 molecule breaks into 2 ions. That is, entropy ( randomness ) increases. As entropy change is positive, it dissolves spontaneously.

Note : Spontaneity does not always depend whether a reaction is exothermic or endothermic.

207aaa134

that's the SIMPLEST QUESTION I HAVE COME ACROSS THIS SITE

smriti.mathur

Ionic bonds have strong electrostatic forces of attraction.Energy is required to overcome these forces.This energy , called the solvation energy, is produced when NH₄Cl (or any ionic compound) is disssolved in polar solvents having high dielectric constant such as water.

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