Id Pb +2

Topics: Acid dissociation constant, Base, Animorphs Pages: 1 (278 words) Published: April 15, 2013
Identifying Pb+2: 1) Took 2mL of my unknown solution and added 2 drops of HCl and got white ppt which correlates with the positive control. 2) Centrifuged the ppt and soln, then discarded soln and washed ppt and centrifuged again. 3) I added 2mL of H2O, put the test tube in the hot water bath and stirred for 3 minute with a stirring rod. 4) I then decanted the solution into another test tube. 5) I added one drop of 6M acetic acid and 3 drops of 1M K2CrO4, which formed a positive confirmation where yellow ppt was formed,therefore it contained Pb+2

Identifying Hg2+2: 1) I took the white ppt formed formed from the first test and added 10 drops of 6M NH3. 2) I stirred the contents and then centrifuged the test tube 3) Whitish ppt stayed and did not dissolve, which is a positive confirmation for Hg2+2, therefore it contains Hg2+2.

Identifying Ag+: 1) decanted the soln from Hg2+2 into another test tube and added 6M HNO3 until it became acidic by litmus paper test 2) no white ppt formed but soln was acidic, which is a negative confirmation because no white ppt was formed, therefore no Ag+ was contained

The observations I made with the Pb+2 was the yellow ppt formed when K2CrO4 was added after the separation. Also with the Hg2+2 was that the ppt did not dissolve completely or at all, meaning that there was Hg2+2 present in the unknown. Lastly, there was no white ppt formed when testing for the separation of Ag+ because there was no Ag+ in the unknown.
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