Can somebody check this for me??
Ksp
AgCl 1.8x10^-10
Ag2CrO4 1.0x10^-12
AgI 1.0x10^-16
Ag3Po4 1.0x10^-16
1. calc the [Ag+] and [Cl-] at equivalence point.
I got 1.3x10^-5
2. Calc. the [CrO4-2] required to precipitate AgCr04 if the [Ag+] equals the conc. cal. in #1
I got 5.56x10^-3
3. calc the [Ag+] in sat. solutions of AgI and Ag3PO4.
I got 1.32x10^-4 for Ag3PO4 and 1x10^-8 for AgI
4. can sodiun chromate be used as an indicator for titration of I- and Ag+? Why?
No, Ksp for Ag2CrO4 larger than Ksp for AgI, AgI would ppt.
5. can sodium chromate be used as an indicator for titration of PO4-3 with Ag+. Why?
No, Ksp for Ag2CrO4 is larger than Ksp for Ag3PO4 so, Ag3PO4 would ppt.
1,2,&3 are good answers.
4&5. Actually, you may not compare solubility products as a point of departure for solubility UNLESS the salts are thw same type. That is, you may compare AgCl and BaSO4 or Ag2CrO4 and Ag2CO3, but you may not compare Ag2CrO4 and AgCl. And I'm not sure about the answer either. The whole point in the AgCl titration using Ag2CrO4 as indicator is that ALL the AgCl ppts, THEN THE NEXT DROP of Ag^+ titrant turns the CrO4^= to Ag2CrO4. So you WANT the AgI and Ag3PO4 to ppt before the next drop turns the Ag2CrO4.
To answer questions 4 and 5, comparing solubility products (Ksp) can be a useful way to determine which salt will precipitate first in a titration. However, it is important to note that solubility products can only be compared if the salts are of the same type. In other words, you can compare the solubility products of salts like AgCl and BaSO4, or Ag2CrO4 and Ag2CO3, but you cannot directly compare the solubility products of Ag2CrO4 and AgCl.
In the titration of AgCl with Ag2CrO4 as an indicator, the goal is to have all of the AgCl precipitate before the next drop of Ag+ titrant turns the CrO4^-2 into Ag2CrO4. Therefore, you would want the salts AgI and Ag3PO4 to precipitate before the Ag2CrO4 forms.
So, based on this information, it seems that the answer provided in question 4 and 5 is correct. Sodium chromate (Na2CrO4) cannot be used as an indicator for the titration of I- and Ag+ (AgI) because the solubility product of Ag2CrO4 is larger than that of AgI, meaning that AgI will precipitate before Ag2CrO4. Similarly, Na2CrO4 cannot be used as an indicator for the titration of PO4^-3 with Ag+ (Ag3PO4) because the solubility product of Ag2CrO4 is larger than that of Ag3PO4, meaning that Ag3PO4 will precipitate before Ag2CrO4.