Guest

When Co(II) cholride is dissolved in concentrated HCl, a blue solution is obtained. Upon dilution with water, the colour changes to pink. Why?

When Co(II) cholride is dissolved in concentrated HCl, a blue solution is  obtained. Upon dilution with water, the colour changes to pink. Why?

Grade:12

1 Answers

Aman Bansal
592 Points
13 years ago

dear madhumita,

If an aqueous solution contains both cobalt(II) and chloride ions, the blue ion CoCl42- forms, in equilibrium with the pink Co2+ (aq) ion.

               
               
    CoCl42- (aq) <===========> Co2+ (aq) + 4Cl1- (aq)  
      Blue   Pink    

At relatively low concentrations of chloride, the equilibrium lies far to the right, and the solution is pink. If there is a large concentration of excess chloride, the equilibrium tends to the left, and the solution tends to be blue.

We are all IITians and here to help you in your IIT JEE preparation.
Now you can win exciting gifts by answering the questions on Discussion Forum. So help discuss any query on askiitians forum and become an Elite Expert League askiitian.
Now you score 5+15 POINTS by uploading your Pic and Downloading the Askiitians Toolbar : Click here to download the toolbar..  
AMAN BANSAL

 

 

 

 

 

Think You Can Provide A Better Answer ?

ASK QUESTION

Get your questions answered by the expert for free