. On adding AgNO3 solution into KI solution a negatively charged colloidal


sol is obtained when they are in

A: 50 mL of 0.1 M AgNO3 + 40 mL of 0.1 M KI

B: 50 mL of 0.1 M AgNO3 + 50 mL of 0.2 M KI

C: 50 mL of 0.2 M AgNO3 + 50 mL of 0.2 M KI

D: None of these

 

Best Answer

Explanation :

The correct answer is option B. 

The basic concept involved is that to form a negatively charged colloid from given solutions,

there should be more KI in comparison to AgNObecause eventually the Ag+ and I- will be involved in Helmholtz double layer formation while other spectator ions will only neutralize them. 

Amongst  the given options,KI is in excess in option B which is given as follows:

A. 50 mL of 0.1 M AgNO= 5mmoles AgNO3

40 ml of 0.1 M KI = 4 mmoles of KI

So, AgNO is comparatively more. 

B. 50 mL of 0.1 M AgNO= 5mmoles AgNO3

50 ml of 0.2 M KI = 10 mmoles of KI

So, KI is in excess

C. 50 mL of 0.2 M AgNO3  = 10mmoles AgNO3

50 ml of 0.2 M KI = 10 mmoles of KI

Equal amount so precipitation occurs. 

Final Answer:

Thus, amongst the given proportions, option B will result in formation of a negatively charged colloidal solution. So, option B is the correct answer. 

 

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