Post Lab Question for the Group III Lab Report that is due on Thursday, June 12, 2014
1)
Devise a separation scheme for confirming Co2+ from a sample that contains all Group III
ions. You may not use thioacetamide to generate sulfides or any other source of
sulfide. All other reagents are in play. Support your scheme with appropriate solubility
product constants (Ksp), formation constants (Kf), and pH values.
Cite your sources!
Post Lab Questions for the Group II Lab Report that is Due May 16, 2014
1)
In step 1 the test solution is heated in the presence of HNO3 to oxidize the Sn(II). What is
the function of the HNO3? What is the function of heating to residue status?
Write a balanced net ionic equations to support your answers. This will require some
research.
2)
In step 1, why is it crucial to use 6M NH3 solution rather than 2 M NaOH solution to make
the residue basic to red litmus? Support your answer with relevant equilibrium constant
values.
3)
In the optional step for Cu(II) confirmation, CH3COOH is used, rather than HNO3 or HCl.
What is the function of the acid? Why aren’t the latter acids used?
4)
Write the balanced complete equation, the balanced total ionic equation, and the
balanced net ionic equation for the positive Sn(II) test in step 7. What type of reaction is
this and give evidence for that choice.