Question

$\left[ CoCl _{4}\right]^{2-}{ }_{(a q)}$ is blue in colour while $\left[ Co \left( H _{2} O \right)_{6}\right]^{2+}{ }_{(a q)}$ is pink. The colour of reaction mixture
$\left[ Co \left( H _{2} O \right)_{6}\right]^{2+}{ }_{(a q)}+4 Cl ^{-}_{(a q)} \rightleftharpoons\left[ CoCl _{4}\right]^{2-}_{(a q)}+6 H _{2} O _{(l)}$ is blue at room temperature while it is pink when cooled hence

• A. reaction is exothermic
• B. reaction is endothermic
• C. equilibrium will shift in forward direction on adding water to reaction mixture
• D. cquilibrium will not shift in forvard dircction on adding water to equilibrium mixture.

Answer 1

Answer: (B)

As on cooling pink colour intensifies so reaction is shifting in backward direction, so reaction must be endothermic.