12 - Chem204 Lecture12 We have been dealing with solutions...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Chem 204 Lecture 12 We have been dealing with solutions where solubility is not an issue. What happens when some of the material doesn’t go into solution? Or precipitates out? Chemically, we have a situation where AX 2 (s) + H 2 O(l) A 2+ (aq) + 2X - (aq) But the equilibrium lies far to the left. K=[A 2+ ]•[X - ] 2 <<1, typical values are 10 -6 to -60 . So very few ions are in solution! (a(AX 2 ) =1)
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture 12 –Page 2 For these situations with essentially insoluble salts, we write K=K sp , the solubility equilibrium constant. This enables us to determine the ion concentrations in equilibrium with the salt. Sometime, this is expressed as solubility or molar solubility, s, the amount in solution. Let’s consider an example.
Background image of page 2
Lecture 12 –Page 3 We will consider the equilibrium with Cr(IO 3 ) 3 (s) (K sp =5.0x10 -6 ) Cr(IO 3 ) 3 (s) + H 2 O(l) Cr 3+ (aq) + 3IO 3 - (aq) I0 0 C+ s + 3 s Es 3 s Solve for the molar solubility, s. K sp = [Cr 3+ ]•[IO 3 - ] 3 = s x (3s) 3 = 27s 4 5.0x10 -6 = 27s 4 and after solving we get: s = 2.1x10 -2 M, this is the molar solubility.
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 11/19/2010 for the course CHEM 204 taught by Professor Gruebele during the Spring '08 term at University of Illinois, Urbana Champaign.

Page1 / 10

12 - Chem204 Lecture12 We have been dealing with solutions...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online