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Chem Lab

Purpose:The purpose of this lab was to analyze unknown solutions to see if it contained the ions Ag, Pb, Hg.
Procedure: For each unknown solution we added 5 drops of cold 6M HCL.Mixed and centrifuged.We tested for complete precipitation by adding an additional drop of 6M HCL. We discarded the dct. and saved the ppt. We washed the ppt twice with 1 ml portions of cold .1M HCL.Discarded the washings both times.Saved the ppt. To the ppt. we added 1 ml of hot water, and placed tube in hot water bath, centrifuged and decant, saved the decant, repeated the hot water step again and saved the decant.To the decant we added 5 drops of the 1M K2CrO4. If the precipitate was yellow it showed the presence of lead.To the ppt. add 6M NH4OH.Mixed and centrifuged.Formation of grayish black ppt.confirms presence of mercury.Decant and save the dct.We put it on a clean wash glass and discard the ppt.To the decant we added 6M HNO3 until the solution was acidic by testing it with litmus paper we were able to determine that silver was or wasn't in the unknown.
Data: #1 #2
Conclusions: This lab taught me how new lab techniques and how easy it is to test unknown solutions for specific ions.
1. In step 1 why was it important to save your ppt? It was necessary because it was needed in the steps that came after number one.
2. Why is Pb dangerous and what are some of the symptoms of lead poisoning?Lead is dangerous because if ingested it could cause lead poisoning and could be deadly, a few symptoms of it is vomiting, slow reflexes, and constipation
3. Describe how you use litmus paper to determine if a solution is acidic or basic? If you put a piece of litmus paper into the solution if it turns pink or stays pink you know its acidic, if it turns blue or stays blue you know it is basic.

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