What products are expected from the disproportionation reaction of hypochlorous acid ?
(a) HClO3 and

Q: Why doesn't the reaction produce chlorine gas ($\text{Cl}_2$)?

While $\text{Cl}_2$ has an oxidation state of $0$, which is lower than $+1$, in aqueous solutions, hypohalites typically disproportionate into the $-1$ halide ion and the $+5$ halate ion due to thermodynamic stability and reaction kinetics.

Q: How do I know it forms $\text{HClO}_3$ and not $\text{HClO}_4$?

The formation of the $+5$ oxidation state (halate) is the most common and kinetically favored pathway for the disproportionation of hypohalites ($+1$ state) at moderate temperatures. Forming the $+7$ state (perhalate) usually requires much stronger oxidizing conditions or further disproportionation of the halate itself.

Q: Is this reaction spontaneous at room temperature?

Yes, the disproportionation of hypochlorous acid is thermodynamically favorable, although the rate can vary depending on concentration, temperature, and the presence of light or catalysts.

Q: What happens if we heat the solution?

Heating the solution generally accelerates the disproportionation reaction, favoring the rapid formation of the halate ($\text{ClO}_3^-$) and halide ($\text{Cl}^-$) ions.

Q: Can other halogens undergo similar reactions?

Absolutely! Bromine and iodine form similar hypohalous acids ($\text{HOBr}$, $\text{HOI}$) which also readily disproportionate into their respective halides ($-1$) and halates ($+5$).

Question

What products are expected from the disproportionation reaction of hypochlorous acid ?

Options:

(A) $	ext{HClO}_3$ and $	ext{Cl}_2	ext{O}$

(B) $	ext{HClO}_2$ and $	ext{HClO}_4$

(C) $	ext{HCl}$ and $	ext{Cl}_2	ext{O}$

(D) $	ext{HCl}$ and $	ext{HClO}_3$

Sigma Percentile · Accepted Answer

### The Dual Life of Hypochlorous Acid: A Tale of Disproportionation

Imagine a single substance acting as both the hero and the villain in a chemical story. In the realm of chemistry, this fascinating phenomenon is known as a **disproportionation reaction**. It occurs when a single element in a compound is simultaneously oxidized (loses electrons) and reduced (gains electrons).

Let's focus on our protagonist for this problem: **hypochlorous acid**, chemically written as $	ext{HOCl}$. To understand its fate, we first need to determine the oxidation state of chlorine within this molecule.

We know the standard oxidation states: hydrogen is typically $+1$, and oxygen is $-2$. Setting up a simple algebraic equation for the neutral molecule:

$$+1 + x + (-2) = 0$$

Solving for $x$, we find that chlorine is in a **$+1$ oxidation state**.

### Splitting Paths: Oxidation and Reduction

Because this is a disproportionation reaction, the chlorine atoms in the $+1$ state will split their paths. Some will travel down to a lower oxidation state (undergoing reduction), while others will climb up to a higher oxidation state (undergoing oxidation).

Chlorine, being a halogen, has several stable oxidation states. The most stable lower state is **$-1$**, which corresponds to the formation of hydrochloric acid ($	ext{HCl}$).

For the higher oxidation state, halogens in hypohalites commonly jump to the **$+5$** state during disproportionation, forming halic acids. In this case, it forms chloric acid ($	ext{HClO}_3$).

### Balancing the Electron Flow

Let's trace the flow of electrons to see how the reaction balances out:

1. **Reduction:** $	ext{Cl}^{+1} \xrightarrow{+2e^-} 	ext{Cl}^{-1}$ (A gain of 2 electrons)
2. **Oxidation:** $	ext{Cl}^{+1} \xrightarrow{-4e^-} 	ext{Cl}^{+5}$ (A loss of 4 electrons)

To ensure the number of electrons lost equals the number gained, we must multiply the reduction half-reaction by 2. This means for every one molecule of $	ext{HOCl}$ that gets oxidized, two molecules of $	ext{HOCl}$ must get reduced.

Combining these gives us the beautifully balanced master equation:

$$3	ext{HOCl} \longrightarrow 2	ext{HCl} + 	ext{HClO}_3$$

### The Final Verdict

Through careful analysis of oxidation states and electron balancing, we can confidently conclude that the disproportionation of hypochlorous acid yields **hydrochloric acid ($	ext{HCl}$)** and **chloric acid ($	ext{HClO}_3$)**. This perfectly aligns with the given options, leading us straight to the correct answer.

Animated Solution for Chemistry - s and p-Block Elements: What products are expected from the disproportionation reaction of hypochlorous acid ?

Select Answer:

Visualized Solution

\text{Disproportionation Reaction}

\text{Oxidation State of Cl in HOCl}

\text{Products of Disproportionation}

\text{Balancing the Reaction}

\text{Final Answer}

The Sigma Insight: Group 17 Elements

The Dual Life of Hypochlorous Acid

Splitting Paths

Balancing the Electron Flow

The Final Verdict

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