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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Dekka on December 19, 2009, 09:50:36 PM

Title: calculating pKsp
Post by: Dekka on December 19, 2009, 09:50:36 PM

Hi all,

I know how to go about calculating Ksp (and then taking the -log to get the pKsp) if I know the substance.

The question is ' a saturated sol'n of mystic hydroxide has a molar concentration of 0.0037.  Calculate the value of the hydroxide.

My(OH)4.'

Any suggestions on how to start this?

Title: Re: calculating pKsp
Post by: sjb on December 20, 2009, 05:03:38 AM

What value of the hydroxide? Concentration? Ksp? Bond length?

Title: Re: calculating pKsp
Post by: Borek on December 20, 2009, 05:17:53 AM

Assuming it is Ksp - write reaction equation for hydroxide dissolution. Can you use reaction stoichiometry to calculate concentrations of all ions involved?

Title: Re: calculating pKsp
Post by: Dekka on December 20, 2009, 05:12:02 PM

I can.. My2(OH)4------> My4+   + 4OH

But really I don't know where to go from here.  (there is no more information in the question)

Title: Re: calculating pKsp
Post by: Borek on December 20, 2009, 05:28:22 PM

OK. You are given solubility, can you calculate concentration of My⁴⁺ & OH^-?

Can you write formula for Ksp?

(Note: I suppose My2 is just a typo).