A 40.0 mL solution containing a mixture of 0.0526 M KCN and 0.0526 M KCl is titrated with 0.0889 M AgNO3 .
What is the concentration of Ag+ at the first equivalence point?
KAgcn=5.97*10^-17
KAgCl=1.77*10^-10
To find the concentration of Ag+ at the first equivalence point, we need to determine the moles of Ag+ and the volume of AgNO3 required to reach the first equivalence point.
First, let's find the moles of Ag+ required to react with all the cyanide ions (CN-) present in the solution:
Moles of CN- = concentration of KCN x volume of solution
= 0.0526 M x 40.0 mL
= 2.1 x 10^-3 moles
Since the reaction is 1:1 between Ag+ and CN-, the moles of Ag+ required will be the same.
Next, let's calculate the volume of AgNO3 required to reach the first equivalence point:
Moles of Ag+ = moles of CN-
Volume of AgNO3 = moles of Ag+ / concentration of AgNO3
= 2.1 x 10^-3 moles / 0.0889 M
= 0.0236 L
= 23.6 mL
Therefore, the volume of AgNO3 required to reach the first equivalence point is 23.6 mL.
Since the concentration of AgNO3 is 0.0889 M, the concentration of Ag+ at the first equivalence point is also 0.0889 M.
To find the concentration of Ag+ at the first equivalence point, we need to understand the reaction that is taking place during the titration.
In this case, AgNO3 is being titrated with a solution containing KCN and KCl. The reaction can be represented as follows:
Ag+ (aq) + CN- (aq) → AgCN(s)
At the equivalence point, all of the KCN in the solution will have reacted with Ag+ to form AgCN. This means that the number of moles of Ag+ added will be equal to the number of moles of KCN initially present in the solution.
First, we need to calculate the number of moles of KCN in the solution:
moles of KCN = concentration of KCN × volume of solution
= 0.0526 M × 40.0 mL
= 2.104 mmol
Since the ratio of KCN to Ag+ is 1:1, the number of moles of Ag+ added will also be 2.104 mmol.
Now, we can calculate the concentration of Ag+ at the first equivalence point:
concentration of Ag+ = moles of Ag+ / volume of solution
= 2.104 mmol / 40.0 mL
= 0.0526 M
Therefore, the concentration of Ag+ at the first equivalence point is 0.0526 M.
If I have not misinterpreted the problem, then
it should be obvious that AgCN will ppt first because of the huge difference in Ksp values AND with (CN^-) and (Cl^-) being the same. If you don't see that you can calculate (Ag^+) for AgCN and AgCl when the first ppt occurs and see that the AgCN ppts first.
That's Ksp = 5.97E-17 = (Ag^+)(CN^-) = (Ag^+)(0.0526) = ?