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cemar.
Feb6-08, 03:15 PM
Hey so im doing a lab write up right now for determining the value of K of the reaction of Fe3+ + SCN- <---> Fe(SCN).
In the procedure for creating dilute solutions for analysis (by colourimetry) we mixed Fe(NO3)3 KSCN and HNO3. I know that the first two will ionize and react to form Fe(SCN) (which is a red pigment) I am however confused with the role that HNO3 plays in the emperiment.
Thanks so much.

chemisttree
Feb6-08, 04:08 PM
The pKa of thiocyanic acid is ~5.4. What is its pKb? How might that affect iron +3 in solution?