ANAL 364: Separations of Group I Cations Patrick Krause ANAL 364: The Chemistry and Qualitative Analysis of Cations: Group Separations and Separations of Group I Cations Patrick Krause CHEM 1108 - Thurs. 1:00pm Dr. Dang-Bachlien 4-4-16 Introduction The purpose of the experiment is to develop the chemistry of cation Group I, II, and III. Also, by demonstrating the separation of Group I, II, and III, using Ag + , Cu 2+ , and Fe 3+ ions. Es- tablishing a procedure for qualitatively verifying the presence of Ag + , Hg 2 2+ , and Pb 2+ ions in an unknown solution. Background The unique chemical properties of these cations makes it possible to separate and verify its presence, even in complex mixtures. One of the simplest but most successful ways to separate one metal cation from another in a mixture is selective precipitation. Thus, one or more cations in solution can be precipitated from other cations in the same solution by the addition of various reagents followed by relatively simple manipulations. When this approach is adopted, two questions immediately arise. Which one of several possible reagents is best? How much of this reagent should be used? The answer to the first ques- tion requires a knowledge of the relative solubilities, hence, the solubility product constants (Ksp), of potential precipitated compounds. The answer to the second question depends on the extent to which the separation must be quantitative. However, even if only a qualitative separa- tion is desired, as in this experiment, a calculation is required involving solubility product con- stants and concentrations of various species in solution.
ANAL 364: Separations of Group I Cations Patrick Krause Chemicals & Safety Procedure I. Separating Selected Group I Cations from Group II and III Cations A. Precipitating Group I Cations (Insoluble Chlorides) Obtained from the laboratory instructor a known solution that is approximately 0.1 M in each of the three cations, Ag + , Cu 2+ , and Fe 3+ ions. With a clean dropper, transferred 15 drops of this mixture into a 75-mm test tube. From a second clean dropper, added dropwise 6M HCl to the mixture in the test tube, while stirring, until the precipitation was complete. Placed the tube containing the mixture in the centrifuge and balanced it with another tube containing an amount of water equal to the volume of the mixture in the tube. Centrifuged for 2 min. Decanted the supernatant liquid, containing, Group II and III cations, from the precipitate
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- Fall '17
- Solubility, Test Tube, supernatant liquid, Patrick Krause