Question

Activity I Questions Answer the following questions based on the tests and observations made in Activity 1: 1. (4 pts) Describe the different colors observed for this system and identify which chemical species is responsible for each color. 2. (4 pts) Provide an interpretation of the behavior observed upon heating and cooling in terms of Le Chatelier's principle.

Answer 1

[CoCl₄]^2- + 6 H₂O $\leftrightharpoons$ 4 Cl^- + [Co(H₂O)₆]²⁺. ∆H < 0 or ∆H=-ve

(1)

Initial color of solution is Blue due to the presence of CoCl₄^2- ion .

After addition of water , equilibrium would shift in the forward direction and color of solution would change to Pink due to the presence of Co(H₂O)₆²⁺ ion .

(2)

According to Le-Chatelier principle , if temperature is increased equilibrium would shift in the direction where heat is absorbed i.e. in direction of endothermic reaction .

The above equilibrium reaction is exothermic in nature . On increasing the temperature(i.e. heating), equilibrium would shift in backward direction and color of solution observed would be blue .

On decreasing the temperature (i.e. cooling), equilibrium would shift in forward direction and color of solution observed would be pink .

Heating = blue

Cooling = pink