Sciencemadness Discussion Board
Not logged in [Login ]
Go To Bottom

Printable Version  
Author: Subject: Ferric thiocyanate...
Hazard to Self

Posts: 56
Registered: 10-12-2003
Location: malaysia
Member Is Offline

Mood: peace

[*] posted on 15-6-2004 at 10:05
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?


[Edited on 17-6-2004 by ahlok2002]

Learning is not state of being; is a process, is not a destination; is a direction
View user's profile Visit user's homepage View All Posts By User This user has MSN Messenger

  Go To Top