`K_(2)Cr_(2)O_(7)+NaoH to CrO_(4)^(2-)`

Options

A. For coloured ppt./Black ppt
B. For coloured solution.
C. for clear/colourless solution
D. For white ppt.

Answer

To solve the question regarding the reaction of potassium dichromate (K₂Cr₂O₇) with sodium hydroxide (NaOH) to form chromate ions (CrO₄²⁻), we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Reactants:**
- We have potassium dichromate (K₂Cr₂O₇) and sodium hydroxide (NaOH) as the reactants.

2. **Write the Balanced Chemical Equation:**
- The reaction between potassium dichromate and sodium hydroxide can be represented as:
\[ K_2Cr_2O_7 + 2NaOH \rightarrow 2NaCrO_4 + K_2O + H_2O \]
- In this reaction, potassium dichromate reacts with sodium hydroxide to form sodium chromate (Na₂CrO₄), potassium oxide (K₂O), and water (H₂O).

3. **Identify the Product:**
- The main product of the reaction is sodium chromate (Na₂CrO₄), which contains the chromate ion (CrO₄²⁻).

4. **Determine the Color of the Solution:**
- Sodium chromate is known to impart a yellow color to the solution. Therefore, when K₂Cr₂O₇ reacts with NaOH, the resulting solution will be colored.

5. **Select the Correct Option:**
- Based on the options provided:
- Option 1: Colored ppt or black ppt
- Option 2: Colored solution
- Option 3: Clear or colorless solution
- Option 4: White ppt
- The correct answer is **Option 2: Colored solution** since the solution will be yellow due to the formation of chromate ions.

### Final Answer:
The reaction of potassium dichromate with sodium hydroxide produces a colored solution (yellow) due to the formation of chromate ions.

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