Separation and Identification of Group C Cations - Foothill College

More documents

Recommendations

Info

Foothill College-Chemistry 1C Qualitative Analysis Group C 3. Complete a proposed flow diagram below for Group C analysis. For each step, indicate the chemical form of each Group C cation that is expected at the given step. Also indicate where in the analysis you will perform a flame test. Ca 2+ , Sr 2+ and Ba 2+ and Group D Dr. L.J. Larson 4 June 27, 2008 QualGroupC.doc
Foothill College-Chemistry 1C Follow-up Questions: Name: For Numerical Problems, you must show all work for credit! 1. Describe the colors emitted by calcium, strontium and barium ions when placed in a flame. Qualitative Analysis Group C 2. Many elements emit light of specific wavelengths when they are placed in a flame. Historically, chemists used such emission “fingerprints” to determine whether certain elements were present in a sample. Some characteristic wavelengths of emission for several elements are: Ag 328.1 nm Fe 372.0 nm Au 267.6 nm K 404.7 nm Cu 324.8 nm Mg 285.2 nm Ni 341.5 nm Na 589.6 nm a) Which of these wavelengths are in the visible part of the spectrum? (Refer to your textbook or another reference source to help you determine this.) b) Which of the above wavelengths has the highest energy per photon? Which has the lowest energy? c) When burned, a sample of an unknown substance is found to emit light of frequency 7.41 × 10 14 s -1 . Which of the above elements is probably in the sample? Show work to support your answer. d) When placed in a flame, copper emits light that appears green to our eyes, evidence that copper exhibits at least one more emission line than the one that is listed above. Referring to your textbook, roughly estimate the wavelength in nanometers of the green emission from copper. 3. A solution that has a pH of 3 is known to contain barium chloride. Ammonium oxalate is added, and no precipitate forms. Ammonia is then added until the solution tests basic to pH paper and a precipitate is observed to form. Explain these observations. Dr. L.J. Larson 5 June 27, 2008 QualGroupC.doc
Page 1 and 2: Foothill College-Chemistry 1C Name:
Page 3: Foothill College-Chemistry 1C Prela

Separation and Identification of Group C Cations - Foothill College

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?