The reaction of K2Cr2O7 with NaCl and conc. H2SO4 givesCrCl3CrOCl2CrO2Cl2Cr2O3

The reaction of potassium dichromate (K2Cr2O7) with sodium chloride (NaCl) and concentrated sulfuric acid (H2SO4) primarily produces chromyl chloride (CrO2Cl2), along with other byproducts. Here's the step-by-step process:

1. Write down the balanced chemical equation for the reaction:

   K2Cr2O7 + 4NaCl + 6H2SO4 → 2CrO2Cl2 + 2K2SO4 + 4NaHSO4 + 3H2O

2. Interpretation of the equation:

   • Potassium dichromate (K2Cr2O7) reacts with sodium chloride (NaCl) and concentrated sulfuric acid (H2SO4) to produce chromyl chloride (CrO2Cl2), potassium sulfate (K2SO4), sodium bisulfate (NaHSO4), and water (H2O).

3. Explanation of the reaction:

   • This is a redox reaction where chromium is reduced from a +6 oxidation state in K2Cr2O7 to a +4 oxidation state in CrO2Cl2.
   • Sodium chloride provides the chloride ions necessary for the formation of chromyl chloride.
   • Concentrated sulfuric acid acts as an oxidizing agent, facilitating the reduction of chromium.

4. Observations:

   • The reaction is characterized by the formation of red fumes of chromyl chloride.
   • Chromyl chloride is a strong oxidizing agent and can further react with organic compounds.

Please note that this reaction should be performed under a fume hood with appropriate safety precautions due to the formation of toxic chromyl chloride gas.