Straight Dope Message Board

[Cardinal]

I'll actually send you money via PayPal or Venmo if you like, for good insight on these questions. I got AP Chemistry materials from a long time teacher who even grades the AP test, but I don't want to bother him with asking for tutoring. So I have some questions on the semester final he gave me that I'm stuck on.

==============
The Ka for HF is 7 E-4, and Ksp for PbF2 is 4 E-8. What is the approximate Kc for the reaction? 2HF + Pb+2 <-- --> PbF2 + 2H- . All are aqueous except PbF2 is solid.

==============

We have a reversible reaction: 2SO2 + O2 <-- --> 2SO3. All are gases.
All are put in a container so that each has a partial pressure of 1.0 atm. At equilibrium, the partial pressure of the product is 1.33 atm. What is Kp of this process?

=============

What is the maximum amount of KCl that can be added to a 50.0 ml sample of 0.200 M Pb(NO3)2 solution before a precipitate forms? Ksp of PbCl2 is 1.3 E-5. 1

[engineer_comp_geek]

Moderator Note

If you want to discuss the actual chemistry questions posed in this thread (without discussing the financial compensation offered), please do so in the GQ thread, which may be found here:

http://boards.straightdope.com/sdmb/...d.php?t=843957 2