Quote:
Originally Posted by that_guy
Heyy folks, im looking for a source or info on what ammonium hydroxide does in spectrophotometry in finding concentration of copper II sulfate. need info fast as the assignments due Wednesday!! if needed ill scan the experiment sheet and email 
cheers,
tony |
Tony it would help if you told us the type of spectrophotometry i.e. UV, IR or visable for colorimetry. Ammoium hydroxide will form as soon as you mix NH3 with water. Normally the OH ion will form a sky blue solid with the Cu2+ ion (not much use for visable analysis) but in this case if it is a concentrated solution of NH4OH a deep blue/purple complex ion will form ([Cu(NH3)6]2+). I can see no real use for ammonium hydroxide to be added to visable spectrum analysis as it is relatively simple to determine the the concentration of CuSO4 using a single or double beam spectrophotometer. You just need a calibration curve and you are off. With IR you have to make little disks where you mix your sample with powdered KBr and put it in a press to squash them together (a real pain as the disks are very fragile) but this is only good for composition and structure. If you use liquids to determine conc in IR spec you must use a cell (cuvettes) made of an insoluble salts like AgCl as glass as most materials absorb and emit IR frequencies and this will muck up your accuracy. I still cannot think of a reason to use ammonium hydroxide.
Mark