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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: mollyp on September 01, 2008, 06:12:18 PM

Title: Calculate total ion concentration of a potassium oxalate solution
Post by: mollyp on September 01, 2008, 06:12:18 PM
Hi,
I am having trouble figuring this:

What is the total ion concentration of a 0.43 M solution of potassium oxalate?

K2C2O4 * H20

Can you get me started?
Thanks!
MOlly
Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: Borek on September 01, 2008, 06:17:59 PM
How does it dissociate?
Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: mollyp on September 01, 2008, 07:30:59 PM
2K+   2C4+  5O2-  2H+

Right?


Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: LQ43 on September 01, 2008, 08:46:14 PM
2K+   2C4+  5O2-  2H+

Right?




No, polyatomic ions do not decompose into their elements in solution (and neither does water)
Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: mollyp on September 01, 2008, 09:12:39 PM
Ok. I am probably overthinking this, but I am totally clueless as to what I need to do to find this. 
Borek, asked me "How does it dissociate?"  Which to me means how does it break into ions.  But, if I have  K2C2O4 + H20  do I have one ion + one water molecule?  I just don't see how to calculate this.
Thank you!
Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: LQ43 on September 01, 2008, 10:45:16 PM
"How does it dissociate?"  Which to me means how does it break into ions. 

Yes, good

But, if I have  K2C2O4 + H20  do I have one ion + one water molecule? 

Not just one ion but yes there is one water molecule 

An example:
 Li2SO4 dissociates into Li+ (but how many Li+ do you get?) and SO42- . Notice what happens to the polyatomic ion. How many ions are there now?

Now what would happen with potassium oxalate?
Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: mollyp on September 01, 2008, 11:09:12 PM
OHHHHHHH!  Yup, I totally did not even think about that oxalate being its own entity...
Ok, so I will have K+ & C2O42-   So I will have 3 total ions, 2 K+ & 1 C2O42-
 
SO,
.43 M x 3mols = 1.3 mols/L

Did I get it?
Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: LQ43 on September 01, 2008, 11:38:36 PM
Yes  :)
Title: Re: Calculate total ion concentration of a potassium oxalate solution
Post by: mollyp on September 02, 2008, 12:11:40 AM
Thank you SO much!  I am so glad I found this site!  I have actually been able to help a few of the people in the High School Chem forum with some of their problems.  Give some, take some!  Fantastic!! ;D