Sodium cobaltinitrite is used in the detection of

Options

A. K
B. Ca
C. Sr
D. Ba

Answer

To answer the question "Sodium cobaltinitrite is used in the detection of," we will follow these steps:

### Step 1: Identify Sodium Cobaltinitrite
Sodium cobaltinitrite is an inorganic compound, and its chemical formula is Na3[Co(NO2)6]. It is a yellow-colored salt.

### Step 2: Understand the Use of Sodium Cobaltinitrite
Sodium cobaltinitrite is primarily used for the qualitative detection of certain alkali metals, specifically potassium (K), calcium (Ca), strontium (Sr), and barium (Ba).

### Step 3: Reaction with Potassium
When sodium cobaltinitrite is mixed with a solution containing potassium ions (K+), a characteristic yellow precipitate of potassium cobaltinitrite (K2[Co(NO2)6]) is formed. This reaction can be represented as follows:

\[ \text{Na}_3[\text{Co(NO}_2)_6] + \text{K}^+ \rightarrow \text{K}_2[\text{Co(NO}_2)_6] \downarrow + \text{Na}^+ \]

The formation of this precipitate indicates the presence of potassium ions in the solution.

### Step 4: Conclusion
Thus, sodium cobaltinitrite is used in the detection of potassium, calcium, strontium, and barium, but it is particularly known for the detection of potassium due to the formation of a distinct yellow precipitate.

### Final Answer
Sodium cobaltinitrite is used in the detection of potassium (K).

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