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Topic: grams of lead(II) sulfide, PBS, will precipitate from 1.00 L of a saturated soln  (Read 5806 times)

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Offline plu

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grams of lead(II) sulfide, PBS, will precipitate from 1.00 L of a saturated soln
« on: February 06, 2006, 06:30:14 PM »
On a similar note to my question on zinc hydroxide solubility:

How many grams of lead(II) sulfide, PBS, will precipitate from 1.00 L of a saturated solution of lead(II) sulfate, PbSO4, if the concentration of sulfide ion, S2-, is adjusted to give a concentration of 1.00 x 10-17 M?
Ksp PbSO4 = 1.6 x 10-8
Ksp PbS = 2.5 x 10-27

I can find the concentration of lead ions in the solution at equilibrium but I don't know how to find the amount of PbS precipitate  :P  *delete me*
« Last Edit: February 06, 2006, 10:03:25 PM by Mitch »
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Offline Borek

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Re:lead(II) sulfide
« Reply #1 on: February 06, 2006, 06:40:16 PM »
Quote from: plu on February 06, 2006, 06:30:14 PM
I can find the concentration of lead ions in the solution at equilibrium but I don't know how to find the amount of PbS precipitate  :P  *delete me*

Really? Ask your students ;)
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Offline plu

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Re:lead(II) sulfide
« Reply #2 on: February 06, 2006, 06:44:35 PM »
:D  Stop mocking me borek and give me a hand here!
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Offline Borek

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Re:lead(II) sulfide
« Reply #3 on: February 06, 2006, 06:54:33 PM »
Well, you understand that it is against forum rules?

Saturated PbSO4 is 1.3*10-4M, after the solution is treated with S2- you are left with 2.5*10-27/10-17=2.5*10-10.

How much was precipitated?

1L*(1.3*10-4-2.5*10-10)=1.3*10-4 mole.

About 30mg.
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Offline plu

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Re:lead(II) sulfide
« Reply #4 on: February 06, 2006, 07:33:40 PM »
Thanks again borek.  I'm just a lowly non-science undergrad guy who's no good with this kind of stuff.  My "students" are just a few high school kids I'm helping out.  I'm no prof  :P
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