Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: matt1234 on 19/05/2006 01:20:01

Title: precipitates and salts
Post by: matt1234 on 19/05/2006 01:20:01

how do i know if a precipitate will form from a mixture.
for example will a precipitate form from this hypothetical mixture,
Na2X (2.5x10^-5M) and MCl (1.4x10^-5M) (Ksp of M2X = 5.6x10^-14)
i just dont get it. thanks if anyone can help.
matt[:)]

Title: Re: precipitates and salts
Post by: DrDick on 25/05/2006 20:18:21

Ksp (given) for M2X = [M+]^2[X-] (at equilibrium)
also
Qsp = [M+]^2[X-] (at given conditions)

If Q = K, then you are at equilibrium, and have a saturated solution - nothing should happen.
If Q < K, then no equilibrium will take place.  Concentration is less than the saturation limit.
If Q > K, then solution has too many dissolved ions, and they will precipitate.

DrDick