Contaminated test solution was the huge problem that

Contaminated test solution was the huge problem that caused many confusions when performing
especially the flame test for Group C. By using a lot of chemical in this experiment, glassware
was easily contained contaminated solution if it was not washed completely. Cations that were
not completely removed after separating also caused the incorrect result for the other tests.
Conclusion:
The identities of the unknown cation in unknown sample #64 were confirmed to be Lead
(II), Iron (III), Strontium (II), Nickel (II), Magnesium, and Zinc. These results were concluded
by the positive results in each specific test for a particular cation. The observations of the
unknown sample were also compared to the observation from the known sample in order to

compared the color of the precipitates. Possible sources of error included the contamination of
the solution containing group C and D when performed the test. Group C ions could be left in the
supernatant after centrifuging which led to the confusion on identifying Group D ions. This
experiment could be improved by carefully wash the precipitate remained after centrifuging, and
re-centrifuge the supernatant in order to confirm the uncontaminated solution for another test.