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Ksp Calculation

  • Thread starter Seinfeld4
  • Start date
  • #1
21
0

Homework Statement



Hi,

I need to calculate the Ksp of Ag2CrO4 based on experimental data.

During the experiment, 1.25g of pure copper was placed in a 1.00 L solution of silver chromate. When the copper was extracted, only 1.24g remained.
Balanced chemical equation: Cu + Ag2CrO4 --> CuCrO4 + 2Ag

The Attempt at a Solution



Here's what I did:

mole of copper = 0.01g / 63.546
= 1.57 * 10^-4

Since volume is 1.00 L, the number of moles is equal to the concentration.
There are 2 moles of Ag and 1 mole of CrO4 for every mole of copper, so:

Ksp = (1.57 * 10^-4) (3.15 * 10^-4) (3.15 * 10^-4)
= 1.56 * 10^-11

But this doesn't seem correct because the actual value is 1.1 * 10^-12.
This would give me a percentage error of over 1000%...

Any help would be much appreciated.
 

Answers and Replies

  • #2
Borek
Mentor
28,351
2,734
Your approach looks correct and the answer seems to be consistent with the data given.

I don't like this question. I wonder how they extracted the copper. Solid left after reaction completed should weigh more, not less.
 
  • #3
21
0
Ok, I thought I was doing it properly. I'm not sure why they made a question that produced a % error greater than 1000. Anyways, thanks Borek!
 
  • #4
1
0
I'm currently working on this same question, lol, can you tell me if the answer to this question was marked correctly? I got the same answers with the same approach.. I know this thread is a year old ._.
 

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