‘A’ is a protecting colloid. The following data is obtained for preventing the coagulation of 10 mL of gold sol to which 1 mL of 10% NaCl is added. What is the gold number of ‘A’?
1
32
2
33
3
35
4
40
Official Solution
Correct Option: (2)
Gold Number Determination Problem
The gold number is defined as the amount (in mg) of a protecting colloid required to prevent the coagulation of 10 mL of a gold sol when 1 mL of 10% NaCl is added.
From the given data:
In the first experiment, 40 mg of A prevents coagulation.
In the second experiment, 35 mg of A prevents coagulation.
In the third experiment, 25 mg of A does not prevent coagulation.
In the fourth experiment, 32 mg of A does not prevent coagulation.
In the fifth experiment, 33 mg of A prevents coagulation.
The gold number is the amount of A required to just prevent coagulation.
Conclusion:
The correct amount for coagulation prevention is 33 mg. Thus, the gold number of ‘A’ is .
02
PYQ 2024
hard
chemistryID: ap-eamce
The following data is obtained for coagulating a positively charged sol in 2 hours:What is the coagulating value of electrolyte for this sol?
1
2
3
4
Official Solution
Correct Option: (2)
The coagulating value of electrolyte is the concentration of the electrolyte which causes precipitation of sol. From the given data, the sol starts precipitating at a concentration of mol L . Hence, the coagulating value of the electrolyte is .
