Alkaline `Noverset(o+)(H)_(4)` salt give brown ppt with `K_(2)HgI_(4)`; brown ppt Is called ______of_____.

Answer

To solve the question, we need to understand the reaction that occurs when an alkaline ammonium salt reacts with Nessler's reagent (K2HgI4). Here’s a step-by-step breakdown of the solution:

### Step 1: Identify the Reagent
The reagent mentioned in the question is K2HgI4, which is known as Nessler's reagent. It is primarily used for the detection of ammonium ions (NH4+).

**Hint:** Remember that Nessler's reagent is specifically used for detecting ammonium ions in qualitative analysis.

### Step 2: Understand the Reaction
When an alkaline ammonium salt (like NH4Cl) is treated with Nessler's reagent in the presence of a strong base (like NaOH), a chemical reaction occurs that produces a brown precipitate.

**Hint:** Consider the role of the strong base in the reaction; it helps in the formation of the ammonium ions.

### Step 3: Write the Reaction
The reaction can be summarized as follows:
- The ammonium ions (NH4+) react with Nessler's reagent (K2HgI4) in the presence of NaOH to form a brown precipitate.

The balanced equation for this reaction can be represented as:
\[ 2 K_2HgI_4 + 4 NaOH + NH_4Cl \rightarrow HgNH_2OI + 7 NaI + 2 KCl + 3 H_2O \]

**Hint:** Pay attention to the stoichiometry of the reactants and products to ensure the equation is balanced correctly.

### Step 4: Identify the Brown Precipitate
The brown precipitate formed in this reaction is referred to as the "iodide of Milan's base." The chemical formula for this brown precipitate is \( NH_2HgO \cdot HgI \).

**Hint:** Recall that the name of the precipitate often includes the term "iodide" and is associated with Milan's base.

### Step 5: Fill in the Blanks
Now, we can fill in the blanks in the original question:
- Alkaline NH4+ salt gives a brown precipitate with K2HgI4; the brown precipitate is called **iodide of Milan's base**.

**Final Answer:**
The brown precipitate is called **iodide of Milan's base**.

### Summary of Steps:
1. Identify the reagent (Nessler's reagent).
2. Understand the reaction with ammonium salts.
3. Write the balanced chemical equation.
4. Identify the brown precipitate (iodide of Milan's base).
5. Fill in the blanks in the question.