The reddish brown gas produced by heating KCl with solid `K_2Cr_2O_7` and conc. `H_2SO_4` is

Options

A. `CrO_2Cl_2`
B. `Cl_2`
C. `CrO_3`
D. `H_2CrO_4`

Answer

To solve the question about the reddish-brown gas produced by heating KCl with solid K2Cr2O7 and concentrated H2SO4, we can follow these steps:

### Step 1: Identify the Reactants
The reactants in the reaction are:
- Potassium Chloride (KCl)
- Potassium Dichromate (K2Cr2O7)
- Concentrated Sulfuric Acid (H2SO4)

### Step 2: Understand the Reaction
When KCl is heated with K2Cr2O7 and concentrated H2SO4, a chemical reaction occurs that leads to the formation of several products.

### Step 3: Write the Balanced Chemical Equation
The reaction can be represented as follows:
\[ 6 \, KCl + K_2Cr_2O_7 + 3 \, H_2SO_4 \rightarrow 2 \, CrO_2Cl_2 + 3 \, K_2SO_4 + 3 \, H_2O \]

### Step 4: Identify the Products
From the balanced equation, we can see that one of the products is CrO2Cl2, which is known as chromyl chloride.

### Step 5: Determine the Color of the Gas
Chromyl chloride (CrO2Cl2) is recognized for its reddish-brown color. Therefore, the reddish-brown gas produced in this reaction is CrO2Cl2.

### Conclusion
The reddish-brown gas produced by heating KCl with solid K2Cr2O7 and concentrated H2SO4 is **CrO2Cl2**.

---