[AntaeusM]

Hey everyone,

I have been struggling with my exams for a long time over this topic, and I can't seem to solve it. I wanted to ask all of you for some help, since my teachers aren't trying to clarify it for me. The problem is as follows:

They gave me the following formula:

Hg₂²⁺+  2IO3^- ---->  Hg2(IO3)₂ ( k)

I have 0.04132 M  25 ml  Hg2(NOI)2   and I add   0.05789 M LIO3  . I have to make a titration out of this.

Now they first want me to add 34 ml 0.05789 M LIO3, after that  36ml 0.05789 M LIO3, then 0.05789 M LIO3 35,69ml(equivalence point), and 40ml 0.05789 M LIO3.
The final question is then, what’s the concentration of Hg2²⁺?

We have to solve this on paper, so we can't test it in lab. I have no idea where to start or how to solve it :/

Thanks for reading.

[AWK]

You have a problem for solubility product with an excess of iodate anion.
Do stoichiometry of precipitation, then calculate an excess concentration od IO3- and put this number into solubilty product of Hg2(IO3)2.

See also
http://answers.yahoo.com/question/index?qid=20081004214835AAjDrnF
http://ctl.scu.edu.tw/scutwebpub/website/DocUpload/CourseTeaching/sylen2007102491212_1.pdf

[AntaeusM]

Thanks a lot. Both links really helped me, I understand the question now and how to solve it.

If possible, do you have more articles like the pdf file? This pdf file is a great addition to study next to the current material that I have to study for my exam. My teacher didn't explain everything and sadly I discovered that the hard way at earlier exams, so if it is possible to have any extra sources about this topic, I would be very grateful. A pdf file or site with practice questions for this topic would be helpful too. Sorry if I am asking too much, just really wanna pass this class this time.

[AWK]

I found them using google in a few seconds

[JGK]

Thanks a lot. Both links really helped me, I understand the question now and how to solve it.

If possible, do you have more articles like the pdf file? This pdf file is a great addition to study next to the current material that I have to study for my exam. My teacher didn't explain everything and sadly I discovered that the hard way at earlier exams, so if it is possible to have any extra sources about this topic, I would be very grateful. A pdf file or site with practice questions for this topic would be helpful too. Sorry if I am asking too much, just really wanna pass this class this time.

You will find that many of the questions set are not totally designed to test your knowledge of a particular subject, but to improve your searching (literature and web searching) skills. In the days before the web (when I was a student), we had to take classes in the use of abstracts and citation indeces in order to find relavent articles.

Rather than asking others to provide information for you, you should improve your skill at finding it for yourself.  Throughout your career it is doubtful you will ever know everything you need, so knowing where to look or how to find it is an important skill to master.