There were a lot inaccurate observations. Some precipitates should appear, but they did not; some precipitate should dissolve, but they did not neither.
The PbCrO4 should dissolved in the nitrate acid based on Appendix 9, but it did not. This might be caused by the supernatant was not removed completely, so the concentration of nitrate acid was decreased and not enough to dissolve the PbCrO4.
The Ba2+ should react with K2CrO4 and form a precipitate based on the Appendix 25, but it did not. The reason for this situation is the amount of precipitate was so small, so it was not noticed. The Ba2+ should also form precipitate in acid and basic sulfide tests based on Appendix 30 and 32, but none of them showed the black precipitates. This should due to the escaping of H2S from the solution, so there was not enough H2S to react with Ba2+.
The Bi2(PO4)3 should not dissolve in the nitrate acid based on the Appendix 37, but it dissolved. This might be caused by the...
... middle of paper ...
... and release CO2 gas.
3. All the CrO42- salts are yellow or orange color.
4. All the hydroxide salts can be dissolved in HNO3.
5. All the PO4- do not dissolve in water.
6. All the nitrate salts are soluble.
7. The sulfates of all metals except lead and barium are soluble.
8. All the metal hydroxides are not soluble, except barium.
In order to improve this lab, a control group can be added. All the cations should be put in another well plate, and some water should be added into all the solution. In this case, the phenomenon of no reaction can be known. The group can be used to compare with any other rows, in order to get more accurate observation.
Overall, this lab is successful. A lot information was explored thought this lab. Even though there were some inaccurate observation caused by unavoidable factors, the results were still acceptable and reasonable.
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