Question

When hydrochloric acid is added to cobalt nitrate solution at room temperature, the following reaction takes place and the reaction mixture becomes blue. On cooling the mixture it becomes pink. On the basis of this information mark the correct answer.

$\underset{pink}{\underset{}{\left[Co\right(H_{2}O{)}_6{]}^{3^{+}}\left(aq\right)}}+4C{l}^{-}\left(aq\right)\leftrightharpoons \underset{blue}{\underset{}{\left[C_{o}C{l}_4{]}^{2^{-}}\right(aq)}}+6H_{2}O\left(l\right)$

• A. $△H>o$ for the reaction
• B. $△H<o$ for the reaction
• C. $△H=o$ for the reaction
• D. The sign of $△H$ canot be predicted on the basis of this information

Answer 1

The correct option is A $△H>o$ for the reaction

On cooling the reaction is moving in backward direction.Thus backward reaction is exothermic.
Hence forward reaction is endothermic~i.e.$△H>o.$