Two questions on solubility

[Triston]

For silver chloride in water Ksp = 1.8 x 10-10. How many moles of silver chloride can be dissolved in 1.0 L of water?

 

If the solubility of CuBr in water is 2.0 x 10-4 mol/L, what is the Ksp of CuBr?

 

I cant even figure out how to start on this. It is not in my textbook, it's not in lecture notes, its not on google. So i havent been able to attempt much.

 

 

If someone could point me in the right direction or even show me how to do an example i would be greatful.

 

Thanks

[mississippichem]

Alright, for the first question lets consider the balanced reaction:

 

[ce] AgCl_{(s)} \rightleftarrows Ag^{+}_{(aq)} + Cl^{-}_{(aq)} [/ce]

 

so, [math] K_{sp} [/math] is given by:

 

[math] K_{sp} = \frac{[Ag^{+}][Cl^{-}]}{[AgCl]} [/math]

 

The activity of the solid [ce]AgCl[/ce] is so close to unity that we can neglect it so we have:

 

[math] K_{sp} = [Ag^{+}][Cl^{-}] [/math]

 

I've brought you very close to an answer on the first question, now just remember that these concentration come in units of [math]mol \cdot L^{-1} [/math].

 

Try this one out, then get back to me about the second question.