. 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 AgNO3 because 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 AgNO3 = 5mmoles AgNO3
40 ml of 0.1 M KI = 4 mmoles of KI
So, AgNO3 is comparatively more.
B. 50 mL of 0.1 M AgNO3 = 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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