Qualitative Analysis of Cations

Activity 2

1. Explain why Pb²⁺ ion, member of group I, may also be found in the group II cations. How can you remove Pb²⁺ from the cation mixtures?
2. Two of the group II cations form soluble hydroxides when ammonium hydroxide is added. What are they and how can you further separate them?
3. Why is it necessary to treat the solution containing group II cations with hydrogen peroxides?

Activity 3

1.  Among group III, which cation precipitates as sulfides and hydroxides upon addition of a base?
2. Sulfide and hydroxides of group II cations precipitate when treated with sulfuric acid. What cation precipitate out and what cations are in the supernatant?
3. Give the balance net equation of the reaction that indicates the presence of Cr⁶⁺.

Activity 4

1. Which among group IV or V forms insoluble/soluble carbonates?
2. Group IV cation is treated with ammonium carbonate, what cation is in the supernatant and the precipitate?

Activity 5

1. What is the color of the flame test for sodium and potassium?
2. Draw the flame test, labeling the luminous, non-luminous, and hottest part of the flame.
3. When doing flame test, what part of the flame will you introduce the compound?

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Answers:

Activity 2

1.