Question

Potassium dichromate acts as a strong oxidizing agent in acidic solution During this process, the oxidation state changes from

• A. $+6$ to $+3$
• B. $+6$ to $+2$
• C. $+3 to +1$
• D. $+2 to +1$

Answer 1

The Correct Option is A

To solve the question of how the oxidation state changes for potassium dichromate (K₂Cr₂O₇) in an acidic solution, we first identify the relevant chemical reaction. Potassium dichromate is known to act as a strong oxidizing agent in acidic conditions. This property is often utilized in various chemical reactions and analytic procedures.

Oxidation State of Chromium in Potassium Dichromate:

• In potassium dichromate (K₂Cr₂O₇), each chromium (Cr) atom initially has an oxidation state of \(+6\).
• Potassium dichromate dissociates in water to form dichromate ions (Cr₂O₇^2-).

Reduction in Acidic Medium:

• When used in an acidic medium, typically involving \(\text{H}^+\) ions, the dichromate ion reduces to form chromic ions \(\text{Cr}^{3+}\).
• The reduction half-reaction for this process can be represented as:

\[\text{Cr}_2\text{O}_7^{2-} + 14\text{H}^+ + 6e^- \rightarrow 2\text{Cr}^{3+} + 7\text{H}_2\text{O}\]

• From this equation, it's evident that each chromium atom is reduced from an oxidation state of \(+6\) to \(+3\).

Conclusion:

• Therefore, the chromium in potassium dichromate changes its oxidation state from \(+6\) to \(+3\).
• The correct answer is

\(+6\) to \(+3\)

• , which confirms the right option among the given choices.

This solution demonstrates potassium dichromate's function as an oxidizing agent, frequently utilized in oxidizing organic compounds and in various analytical methods due to its ability to reduce from \(+6\) to \(+3\).