ATAR Notes: Forum
VCE Stuff => VCE Science => VCE Mathematics/Science/Technology => VCE Subjects + Help => VCE Chemistry => Topic started by: coezooke on April 16, 2013, 11:06:48 pm
-
37) AAS and UV-Bis spectroscopy both involve absorption of light. Both can be used to determine the amount of copper in a solution. B) Which technique would be simplest for the analysis of an approximately 0.5M copper nitrate solution? Explain your answer.
They both require standards to be made, analysed and recorded so I don't understand which technique is simpler than the other. Can someone please help, and thank you in advance. :)
-
37) AAS and UV-Bis spectroscopy both involve absorption of light. Both can be used to determine the amount of copper in a solution. B) Which technique would be simplest for the analysis of an approximately 0.5M copper nitrate solution? Explain your answer.
They both require standards to be made, analysed and recorded so I don't understand which technique is simpler than the other. Can someone please help, and thank you in advance. :)
I'm not 100% sure as to what the exact answer is but I think it might be UV-Vis as there will be way too many dilutions required to get the results within the calibration range if AAS was used. Again, not sure on this so get a second answer. :D
Also, Question 36) b-, not 37 if anyone needs to refer to the textbook. :)
-
My edition doesn't have a solution - I asked my teacher the other day and he said he would have answered AAS, because the use of a cathode lamp to produce the specific wavelengths for copper is easier and more accurate than using monochromators to select a narrow wavelength band for UV-Vis.
The Heinemann book seems pretty crap though, most of the questions don't have solutions at all :/
-
Riversong is right, AAS is used to measure very small concentrations (ppm / ppb). 0.5M is much stronger than this and thus would required much greater dilution. The solutions to worded questions such as this one are contained on the CD in the back of the book, if you didn't get one, ask your teacher is he knows where they might be.
Hope this helps.
-
This is from the solutions:
A36.
a i The copper hexaaqua ion, Cu(H2O)62+
ii Cu atoms
b UV–visible spectroscopy would be the easiest technique to determine the concentration of a 0.5 M copper nitrate solution; AAS would require several dilutions in order to bring the concentration of copper into the linear range of the calibration curve.
c i White light is passed through a monochromator or wavelength selector.
ii A hollow cathode lamp containing a cathode composed of the element under investigation produces light of the required wavelength.
-
Firstly, they'd really make you response with copper hexaaqua?
Secondly, to be more precise, as copper is a transition metal, you have to write the oxidation state of copper in as copper hexaaqua (II)