Question

For idometric titration of copper, why is HCl added to KIO3 and then titrated immediatedly?

What would happen if iodine-thiosulfate titration was done in a highly acidic solution?

If the copper reaction solution was basic, how would the iodine-thiosulfate reaction be influenced?

Answer 1

a)Oxygen can oxidize iodide to I2 so you want to minimize that possibility (more I2 causes more thiosulfate to be used and results for Cu are high).

b) I don't know if this refers to the titration itself or if it refers to the Cu determination. If the Cu, you want it buffered between about 4.5 and 5.5 or so.

c) To basic and the hydroxide ppts

Answer 2

a)Oxygen can oxidize iodide to I2 so you want to minimize that possibility (more I2 causes more thiosulfate to be used and results for Cu are high).

b) I don't know if this refers to the titration itself or if it refers to the Cu determination. If the Cu, you want it buffered between about 4.5 and 5.5 or so.

c) Too basic and the hydroxide ppts