Question

Which of the following statements are correct for this exothermic reaction ?
$\left[CoC{l}_4{]}^{2-}\right(aq)+6H_{2}O(l)\rightleftharpoons [Co\left(H_{2}O{)}_6{]}^{2+}\right(aq)+4C{l}^{-}(aq)$
(Consider initially only $[CoC{l}_4{]}^{2-}$ is added to water)

• A. If $HCl$ is added to above equilibrium then concentration of $\left[CoC{l}_4{]}^{2-}\right(aq)$ will increase
• B. On dilution with water the concentration of $\left[CoC{l}_4{]}^{2-}\right(aq)$ will decrease
• C. On doubling the volume of solution by addition of water the final concentration of $\left[Co\right(H_{2}O{)}_6{]}^{2+}$will be double than its initial concentration
• D. On increasing temperature the concentration of $\left[CoC{l}_4{]}^{2-}\right(aq)$ will increase

Answer 1

Answer: (A), (B), (D)

If $HCl$ is added to above equilibrium then concentration of $\left[CoC{l}_4{]}^{2-}\right(aq)$ will increase
On dilution with water the concentration of $\left[CoC{l}_4{]}^{2-}\right(aq)$ will decrease
On increasing temperature the concentration of $\left[CoC{l}_4{]}^{2-}\right(aq)$ will increase

On adding $C{l}^{-}$ ion the equilibrium will shift in the backward direction, so $[CoC{l}_4{]}^{2-}$ will increase.
On dilution, the volume will increase which results in a decrease in concentration of $[CoC{l}_4{]}^{2-}$Though the amount of $\left[Co\right(H_{2}O{)}_6{]}^{2+}$ will get increased but its concentration cannot get doubled as volume has increased.
As the reaction is exothermic in nature so increasing temp will shift equilibrium is a backward direction.