Describe the steps and reagents necessary to separate and identify Pb^2+ ion fro
ID: 483849 • Letter: D
Question
Describe the steps and reagents necessary to separate and identify Pb^2+ ion from a mixture containing AgCl(s) and PbCl _2 (s) salts. Describe the correct way to wash a precipitate. Why is it necessary to wash a precipitate in any qualitative analysis experiment? How do you decant a supernatant liquid from a small test tube? What group reagents are used to precipitate Group I and Group II cations? Describe the proper operation of a centrifuge. Why does glassware used in qualitative analysis have to be well washed and then rinsed with distilled water? 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. Define corrosive substance. Define toxic substance What are the chemical hazards involved when using 6 M HCl, and dilute solutions of silver nitrate (AgNO _3) and lead nitrate (Pb(NO _3) _2).Explanation / Answer
5. PbCl2 is soluble in hot water whereas, AgCl remains insoluble in hot water. both were insoluble in cold water. So they can be easily separated by pouring hot water.
6. A precipitate is washed with the solvent in which it is completely immiscible. It is important to wash off any unwanted adhered impurities by washing a precipitate and thus this step is needed.
7. A supernatant liquid can be decanted by either centrifugation of the liquid first where, the solid settles down or by simply pouring the liquid out.
8. Reagent to precipitate Group I cations in dilute HCl forming chlorides of cations. For group II cations, we pass H2S in the acidic solution, wherein, the cations precipitate out as sulfides.
9. Centrifugation is done by uring the mix in the centrifuge tube and rotating it at high speed while balancing the tube. The tube is allowed to settle for sometime and then the supernatant liquid is pured out of it. The solid is washed with the solvent several times by the same method of centrifugation.
10. In qualitative analysis even a trace amount of other impurity may result in incorrect analysis and thus the glasswares must be thoroughly washed prior to the experiment.
11. Bunsen burner provides much greater temperature as opposed to boiling water temperature and thus to avoid any side reactions of the cations in solution with added reagent, we do not used bunsen burner.
12. a) Corrosive substance is one which leaches out any other substance when it comes in contact with it, practically destroying it. b) toxic substance is one which is harmful to health. c) HCl is corrosive and highly toxic material. AgCl is an irritant. Pb(NO3)2 is harmful to skin when it comes in contant and has prolonged ill effects on health.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.