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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Soyeon on March 04, 2018, 11:03:43 PM

Title: determining equilibrium constant
Post by: Soyeon on March 04, 2018, 11:03:43 PM

Hi, my lab is about determining equilibrium constant and I need to make a calibration curve about absorbance and concentration of FeSCN 2+.

The concentration of Fe3+ solution is 0.150M, and SCN- solution is 5.00x10^-4 M. And I also usded HNO3 solution

Solution      Volume of Fe3+   Volume of SCN-     Volume of HNO3
1                    10.00                     0                         15.00
2                    10.00                    2.00                      13.00
3                    10.00                    5.00                     10.00
4                    10.00                    8.00                     7.00
5                    10.00                    10.00                   5.00

How can I calculate the concentration of FeSCN2+ (the complex)?               

Title: Re: determining equilibrium constant
Post by: Borek on March 05, 2018, 02:55:54 AM

Quote from: Soyeon on March 04, 2018, 11:03:43 PM

How can I calculate the concentration of FeSCN2+ (the complex)?

In general you can't without knowing the equilibrium constant or the molar absorptivity, but perhaps there is something about the procedure that makes it possible.