Qualitative Analysis: Test For Cations! Trivia Quiz

1. Forms a Blue Precipitate when aqueous Ammonia is added, that redissolve in the excess reagent to form a dark blue solution.

Cu2+ ions form a blue precipitate when aqueous ammonia is added. This precipitate can then redissolve in the excess ammonia to form a dark blue solution. Therefore, the correct answer is Cu2+.

Explanation

Cu2+ ions form a blue precipitate when aqueous ammonia is added. This precipitate can then redissolve in the excess ammonia to form a dark blue solution. Therefore, the correct answer is Cu2+.

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2. Forms a Reddish-Brown Precipitate when aqueous Ammonia is added, that does not redissolve in the excess reagent.

When aqueous ammonia is added to a solution containing Fe3+, it forms a reddish-brown precipitate. This precipitate does not redissolve even when excess ammonia is added. This indicates the presence of Fe3+ in the solution.

Explanation

When aqueous ammonia is added to a solution containing Fe3+, it forms a reddish-brown precipitate. This precipitate does not redissolve even when excess ammonia is added. This indicates the presence of Fe3+ in the solution.

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3. Forms a Blue Precipitate when Sodium Hydroxide is added, which does not redissolve in the excess reagent.

Cu2+ forms a blue precipitate when Sodium Hydroxide is added. This indicates the presence of Cu2+ ions in the solution. The blue precipitate does not redissolve in the excess reagent, suggesting that it is insoluble. Therefore, Cu2+ is the correct answer.

Explanation

Cu2+ forms a blue precipitate when Sodium Hydroxide is added. This indicates the presence of Cu2+ ions in the solution. The blue precipitate does not redissolve in the excess reagent, suggesting that it is insoluble. Therefore, Cu2+ is the correct answer.

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4. Forms a Dirty Green Precipitate when Sodium Hydroxide is added, which does not redissolve in the excess reagent.

When Sodium Hydroxide is added to a solution containing Fe2+, it forms a dirty green precipitate. This precipitate does not redissolve when excess Sodium Hydroxide is added. Therefore, the correct answer is Fe2+.

Explanation

When Sodium Hydroxide is added to a solution containing Fe2+, it forms a dirty green precipitate. This precipitate does not redissolve when excess Sodium Hydroxide is added. Therefore, the correct answer is Fe2+.

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5. Forms a Reddish Brown Precipitate when Sodium Hydroxide is added, which does not redissolve in the excess reagent.

When sodium hydroxide is added to a solution containing Fe 3+, it forms a reddish-brown precipitate. This precipitate does not redissolve when excess sodium hydroxide is added. This is due to the formation of a complex compound called iron(III) hydroxide, which is insoluble in water. The reddish-brown color of the precipitate is characteristic of Fe 3+ ions. Therefore, the presence of a reddish-brown precipitate that does not redissolve confirms the presence of Fe 3+ ions in the solution.

Explanation

When sodium hydroxide is added to a solution containing Fe 3+, it forms a reddish-brown precipitate. This precipitate does not redissolve when excess sodium hydroxide is added. This is due to the formation of a complex compound called iron(III) hydroxide, which is insoluble in water. The reddish-brown color of the precipitate is characteristic of Fe 3+ ions. Therefore, the presence of a reddish-brown precipitate that does not redissolve confirms the presence of Fe 3+ ions in the solution.

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6. Forms a Dirty Green Precipitate when aqueous Ammonia is added, that does not redissolve in the excess reagent.

When aqueous ammonia is added to Fe2+, it forms a dirty green precipitate. This precipitate does not redissolve in the excess reagent. Based on this information, the correct answer is Fe2+.

Explanation

When aqueous ammonia is added to Fe2+, it forms a dirty green precipitate. This precipitate does not redissolve in the excess reagent. Based on this information, the correct answer is Fe2+.

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7. Forms a White Precipitate when aqueous Ammonia is added, that redissolves in the excess reagent.

When aqueous ammonia is added to a solution containing Zn 2+, a white precipitate is formed. This white precipitate is the result of the reaction between Zn 2+ and the hydroxide ions (OH-) from the ammonia. However, the precipitate redissolves when excess ammonia is added because it forms a complex ion with Zn 2+, which is soluble in excess ammonia. Therefore, the presence of a white precipitate that redissolves in excess reagent confirms the presence of Zn 2+ in the solution.

Explanation

When aqueous ammonia is added to a solution containing Zn 2+, a white precipitate is formed. This white precipitate is the result of the reaction between Zn 2+ and the hydroxide ions (OH-) from the ammonia. However, the precipitate redissolves when excess ammonia is added because it forms a complex ion with Zn 2+, which is soluble in excess ammonia. Therefore, the presence of a white precipitate that redissolves in excess reagent confirms the presence of Zn 2+ in the solution.

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8. Forms a White Precipitate when Sodium Hydroxide is added, which does not redissolve in the excess reagent.

When Sodium Hydroxide is added to a solution containing Mg2+ and Ca2+, a white precipitate is formed. This precipitate does not redissolve in the excess reagent. Therefore, the correct answer is Mg2+, Ca2+, Ca2+, Mg2+.

Explanation

When Sodium Hydroxide is added to a solution containing Mg2+ and Ca2+, a white precipitate is formed. This precipitate does not redissolve in the excess reagent. Therefore, the correct answer is Mg2+, Ca2+, Ca2+, Mg2+.

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9. Forms NO Precipitate when aqueous Ammonia is added

When aqueous ammonia is added to a solution containing Ca2+ and NH4+, no precipitate forms. This is because Ca2+ and NH4+ ions do not react with ammonia to form an insoluble compound. In other words, the combination of Ca2+ and NH4+ ions with ammonia does not result in the formation of a solid that would precipitate out of the solution. Therefore, the correct answer is Ca2+, NH4+, NH4+, Ca2+.

Explanation

When aqueous ammonia is added to a solution containing Ca2+ and NH4+, no precipitate forms. This is because Ca2+ and NH4+ ions do not react with ammonia to form an insoluble compound. In other words, the combination of Ca2+ and NH4+ ions with ammonia does not result in the formation of a solid that would precipitate out of the solution. Therefore, the correct answer is Ca2+, NH4+, NH4+, Ca2+.

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10. Forms a White Precipitate when Sodium Hydroxide is added, that redissolves in the excess reagent.

When sodium hydroxide is added to a solution containing Pb2+, Zn2+, and Al3+, it forms a white precipitate. However, this precipitate redissolves in the excess reagent. Therefore, the correct answer is Pb2+, Zn2+, Al3+.

Explanation

When sodium hydroxide is added to a solution containing Pb2+, Zn2+, and Al3+, it forms a white precipitate. However, this precipitate redissolves in the excess reagent. Therefore, the correct answer is Pb2+, Zn2+, Al3+.

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11. Forms a White Precipitate when aqueous Ammonia is added, that does not redissolve in the excess reagent.

When aqueous ammonia is added to a solution containing Pb2+, Mg2+, and Al3+, a white precipitate is formed. This precipitate does not redissolve in the excess reagent, indicating that it is insoluble. Therefore, the correct answer is Pb2+, Mg2+, Al3+.

Explanation

When aqueous ammonia is added to a solution containing Pb2+, Mg2+, and Al3+, a white precipitate is formed. This precipitate does not redissolve in the excess reagent, indicating that it is insoluble. Therefore, the correct answer is Pb2+, Mg2+, Al3+.

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