[bucky91]

A water sample contains 1.0 x 10^-4 M of Pb(II) and 0.75 M Cl-. Assuming that no reactions other than that between lead and chlorine occur, what fraction of all of the lead species will Pb^2+ be at equilibrium?

Please help...I've been stuck for ages and have no idea what to do :S

[sjb]

A water sample contains 1.0 x 10^-4 M of Pb(II) and 0.75 M Cl-. Assuming that no reactions other than that between lead and chlorine occur, what fraction of all of the lead species will Pb^2+ be at equilibrium?

Please help...I've been stuck for ages and have no idea what to do :S

Solubility product?

[bucky91]

...?

[Arkcon]

This problem will require you to use the solubility product, from a table in your book or elsewhere, or given to you in another part of this problem.  Look here, there are some solved practice problems:  http://chemed.chem.purdue.edu/genchem/topicreview/bp/ch18/ksp.php

[bucky91]

Thanks!

This is what I've done so far...no idea if it's right or wrong though :s

Pb²⁺ + Cl^- <---> PbCl⁺

PbCl⁺ + Cl^- <---> PbCl₂

PbCl₂ + Cl^- <---> PbCl₃^-

PbCl₃^- + Cl^- <---> PbCl₄^2-

For the 1st equation: K1 = [PbCl⁺]
                                    [Pb²⁺][Cl^-]

The questions says that: [Pb²⁺] = 1.0 x 10^-4 M
                                     [Cl^-] = 0.75 M

This site: http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/The-Solubility-Product-622.html  gives the solubility product for PbCl2 as: 1.6 × 10-5. So would this be K2? How do I find K1 then? Or am I totally off track here...

I have such a hard time with all this K stuff

[sjb]

Thanks!

This is what I've done so far...no idea if it's right or wrong though :s

Pb²⁺ + Cl^- <---> PbCl⁺

PbCl⁺ + Cl^- <---> PbCl₂

PbCl₂ + Cl^- <---> PbCl₃^-

PbCl₃^- + Cl^- <---> PbCl₄^2-

For the 1st equation: K1 = [PbCl⁺]
                                    [Pb²⁺][Cl^-]

The questions says that: [Pb²⁺] = 1.0 x 10^-4 M
                                     [Cl^-] = 0.75 M

This site: http://chemed.chem.wisc.edu/chempaths/GenChem-Textbook/The-Solubility-Product-622.html  gives the solubility product for PbCl2 as: 1.6 × 10-5. So would this be K2? How do I find K1 then? Or am I totally off track here...

I have such a hard time with all this K stuff

No, Ksp refers to Pb²⁺(aq) + 2Cl^-(aq)  PbCl₂(s); so a combination of K1 and K2