Physical Chemistry by Ball David W Edition 2nd ISBN 97811339

Physical Chemistry

by Ball, David W.

Edition: 2nd

ISBN: 9781133958437

Format: Hardcover

Pub. Date: 1/1/2014

3.63. A spontaneous, endothermic chemical reaction mentioned at the beginning of this chapter was Ba(OH)2.8H20(s) + 2NH,SCN(s) Ba(SCN)2(s) + 2NH3(g) + 10H20(e) Without having specific values of S for all of these substances, would you expect AS for the reaction to be positive or negative? Does your answer support the spontaneity of this reaction?

Solution

First of all, entropy is the measure of randomness and follows the order

Solid< liquid<gas

In the given forward reaction, randomness increased, since two moles of gaseous NH3 and 10 moles of water (l) are formed.

So entropy Change is possible which chareteristic property for spontaneous reaction.

Hence it is spontaneous reaction.