Friday
August 22, 2014

Homework Help: chemistry

Posted by bria on Wednesday, September 13, 2006 at 2:21pm.

If a solution of 0.10 M silver nitrate, AgNO3, is slowly added to a solution containing 0.010 M potassium iodate, KIO3, and 0.20 M sodium bromate, NaBrO3, what precipitate will form first. Will this precipitate form nearly completely (99%) before the second precipitate starts to form?
Qsp of AgIO3 is 3.6 * 10^-8 and the Qsp of AgBrO3 is 5.01 * 10^-5


I think you are using Qsp incorrectly. I believe the values you list are Ksp values and not Qsp.
For the first part, write the Ksp expression for AgIO3 and for AgBrO3. Using 0.01 for (IO3^-) and 0.2 for (BrO3^-), calculate (Ag^+) necessary to cause precipitation of each salt. Since AgNO3 is being added slowly, the first ppt will be that requiring the smaller (Ag^+). Let's digest this one before we start on the 2nd part. I hope this helps


For the second part, technically, I don't think it can be done exactly because there are no volumes given for KIO3 and KBrO3. However, since the molarities of KIO3 and KBrO3 are so different, I suspect that the author assumed dilution would not play a factor and you are to make this comparison based on molarity at the beginning and at the end. If I have assumed correctly, then proceed by taking the ratio of the Ksp values.
[(Ag^+)(IO3^-)/(Ag^+)(BrO3^-)]=[Ksp AgNO3/Ksp AgBrO3]= 3.6E-8/5.01E-5.

Note that (Ag^+) cancels.
Solve for (IO3^-) = ?? x (BrO3^-)
At the moment just before the first molecule of AgBrO3 ppts, (BrO3^-) = 0.2 (assuming no dilution effects in pptg the AgIO3 at the beginning) and this will give you the molarity of the (IO3^-) at that point before any AgBrO3 has pptd.

Then compare that to the 0.01M it was at the beginning. Doing this results in about 98.5% (approximately--you will need to do it more exactly) pptn (or about 1.5% not pptd). Check my thinking. Check my arithmetic. In a separate process, I assumed some volumes, such as 50 mL KIO3 and 50 mL KBrO3 and worked through the dilution part and came up with only minor differences; i.e., only about 0.01% difference, and that makes me think the author assumed no dilution effects. I hope this helps.


Thank you so much for you help.


Hello! Good Site! Thanks you! grtylvxpjyjsp

Answer this Question

First Name:
School Subject:
Answer:

Related Questions

Chemistry - 0.658 g of potassium bromate and 0.562 g of silver nitrate are added...
Chem - Solutions of sodium carbonate and silver nitrate react to form solid ...
Chemistry - 0.10 M potassium chromate is slowly added to a solution containing 0...
chemistry - If 0.10 M potassium chromate is slowly added to a solution ...
Chemistry - The values of Ksp for silver bromide, AgBr is 7.7x10^-13, and silver...
chemistry - 0.10 M potassium chromate is slowly added to a solution containing 0...
chemistry - explain why a precipitate forms when silver nitrate solution is ...
Chemistry - A solution contains an unknown mass of dissolved silver ions. When ...
CHemistry Please Help..............LAB - Standardization of the Sodium ...
Chemistry - A solution contains the following ions: Hg2(2+) and Fe(2+). When ...

Search
Members