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Topic: Solubility + Common Ion Effect  (Read 3864 times)

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Offline student8607

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Solubility + Common Ion Effect
« on: March 17, 2009, 12:17:20 PM »
Calculate the molar solubility of MgF2 in 0.1M MgCl2 at 25 degrees Celsius

The Ksp = 7.4x10-11

7.4x10-11 = (0.1)(2x)2
4x2 = 0.1/7.4x10-11
divide by 4
take the square root
x = 18380

but I don't believe that is right?
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Offline Borek

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Re: Solubility + Common Ion Effect
« Reply #1 on: March 17, 2009, 12:18:39 PM »
Quote from: student8607 on March 17, 2009, 12:17:20 PM
7.4x10-11 = (0.1)(2x)2
4x2 = 0.1/7.4x10-11

Chek your math.
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Offline student8607

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Re: Solubility + Common Ion Effect
« Reply #2 on: March 17, 2009, 12:21:18 PM »
Ohhh now I see.
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Offline student8607

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Re: Solubility + Common Ion Effect
« Reply #3 on: March 17, 2009, 12:22:33 PM »
7.4x10-11 = (0.1)(2x)2
7.4x10-11 / 0.1 = (2x)2


Now I get 1.36 x 10-5 . thanks
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Offline student8607

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Re: Solubility + Common Ion Effect
« Reply #4 on: March 17, 2009, 01:30:10 PM »
ANOTHER question:

A particular saturated solution of PbI2 has a Ksp of 8.45 x 10-9
If [Pb2+] = 2.5x10-4 what is [I-]

8.45x10-9 = [(2x)2] [2.5x10-4]
3.38x10-5 = 2x2
divide by 4
take square root
got 0.00291?
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