Ferric thiocyanate...
When i added the ferric sulphate with potassium thiocynate in water the red-orange ferric thiocyanate (FeNCS3) was formed. Then, i took the UV abs at
480nm, and then i expose the solution at visible light for 5, 10, 15, 20.....minutes and took the reading again at same wavelength. i noticed that the
reading was decreasing.
What is the purpose expose to light? i know the Fe2NCS3 is not stable and can exist as FeNCS2+ in water.
If what i propose is correct, then i will get decreasing value of the ABS when the solution was exposing to longer time of sun light this is due to
dissociation???
Fe3+ + NCS- → [Fe(NCS)]2+
[Fe(NCS)]2+ + NCS- →[ Fe(NCS)2 ]1+
[Fe(NCS)2] 1+ + NCS- → Fe(NCS)3
So if I expose to sun light then will cause the reaction to be backward? As a result a get lower ABS when the solution expose longer?
I try to add acetone rather than water for the same experiment, I notice the reading of the ABS were decresing when exposing the solution with sun
light.
Later, i plot the graph with ABS versus time of exposing to sun light, i got two decresing lines as increasing time. The value of absorbance for the
reaction in acetone always higher than in the water in the graph.
What is the conclusion I can tell from the observation?
Is the acetone creating less polar environment to favorable the reverse of the reaction as stated above? so i can detect more ferric thiocynate
formation?
Thanks!
[Edited on 17-6-2004 by ahlok2002]
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