Report he General Chemistry and Qualitative Analysis II Laboratory (CHE2021.)-Sp
ID: 565280 • Letter: R
Question
Report he General Chemistry and Qualitative Analysis II Laboratory (CHE2021.)-Spring 2018 Whe 1. (8 pts.) Describe the general principle of qualitative analysis. How is qualitative analysis different from quantitative analysis? e2 pts.) Define selective precipitation? If you had a solution that contains Ag Cu and Fe how would you separate the metal ions by selective precipitation? 0. (8 pts ) what is the common-ion effect? Give an example to illustrate how a common-ion affects the solubility of a slightly soluble ionic compound? 4 (8 pts) Evplain the difference between solubility and solubility product of a 5. (8 pts) Describe the steps and reagents necessary to separate and identity Pb 6. 8 pts.) Describe the correct way to wash a precipitate. Why is it necessary to slightly soluble ionic compound ion from a mixture containing AgCI(s) and PbCl: (s) salts wash a precipitate in any qualitative analysis experiment? 7 (8 pts.) How do you decant a supernatant liquid from a small test tube? (8 pts.) What group reagents are used to precipitate Group I and Group II cations? 8. 9. (8 pts.) Describe the proper operation of a centrifuge. 10. (9 pts). Why does glassware used in qualitative analysis have to be well washed and then rinsed with distilled water? 11. (9 pts.) In qualitative analysis, a hot water bath is used to heat a solution containing the cation mixture. The solutions are not heated directly with a Bunsen burner. Explain why 12. (9 pts) a) Define corrosive substance. b) Define toxic substance. c) What are the chemical hazards involved when using 6 M HCl, and dilute solutions of silver nitrate (AgNO3) and lead nitrate (Pb(NO3)2).Explanation / Answer
Qualitative analysis is used to find the identity of unknown ions in a solution, these ions can be removed from the solution by adding an anion and forming insoluble salts that will precipitate.
Quantitative analysis is used to determine "how much of the ion" is in the solution.
qualitative analysis is "what is" in the sample
quantitative analysis is "how much is" in the sample
Selective precipitation is a technique to make a ion precipitate before others, this is done by adding different reagents that will produce a know soluble salt according to the ions present in the solution.
Ag will precipitate with the addition of HCl, this will produce AgCl (s) a white precipitate
Fe+2 will precipitate with the addition of NaOH, this will produce Fe(OH)2
Cu will precipitate by using H2S, this will produce CuS (black precipitate)