Question

A student analyzed an unknown sample that contained a single anion. The sample gave a yellow precipitated upon addition of a solution of AgNo3 which did not dissolve in ammonia. Which anion is present in the unknown solution? Write the corresponding net ionic equation.

Answer 1

Answer:

Anion present- Iodide ion (I⁻)

Net ionic equation- Ag⁺(aq) + I⁻(aq) → AgI(s)

Explanation:

In order to answer the question, we need to have an understanding of insoluble salts or precipitates formed by silver metal.

Additionally we need to know the color of the precipitates.

Some of insoluble salts of silver and their color include;

• Silver chloride (AgCl) - white color
• Silver bromide (AgBr)- Pale cream color
• Silver Iodide (AgI) - Yellow color
• Silver hydroxide (Ag(OH)- Brown color

With that information we can identify the precipitate of silver formed and identify the anion present in the sample.

• The color of the precipitate formed upon addition of AgNO₃ is yellow, this means the precipitate formed was AgI.
• Therefore, the anion that was present in the sample was iodide ion (I⁻).
• Thus, the corresponding net ionic equation will be;

Ag⁺(aq) + I⁻(aq) → AgI(s)