KMnO₄ + HCl | Potassium Permanaganate and Hydrochloric Acid Reaction

Aqueous hydrochloric acid (HCl) reacts with potassium permanganate (KMnO₄) to produce potassium chloride (KCl), Manganese chloride (MnCl₂), water (H₂O) and chlorine gas (Cl₂). So purplish colour solution will turn in to a colourless or light pink colour solution. Colour changes, balanced reaction, ionic equation of KMnO₄ + HCl reaction are discussed in this tutorial.

2KMnO_4(s) + 16HCl _(aq) = 2KCl _(aq) + 2MnCl_{2 (aq)} + 8H₂O _(l) + 5Cl_2(g)

Aqueous hydrochloric acid and solid potassium permanganate reaction

Potassium permanganate is available in solid form. But It is very much soluble in water. Dissolve a little bit of KMnO₄ in water and then it will give a purple colour solution. When you add hydrochloric acid, you can see and emission of gas bubbles which is relevant to chlorine gas.

Colour changes when KMnO₄ reacts with HCl

When reaction happens continuously purple colour of the solution is reduced with time and a colourless or light pink solution will be given when old KMnO₄ is reactant.

Hydrochloric acid is a strong acid and can release H⁺ ions and Cl^- ions to the solution. And also hydrochloric acid is a colourless solution.

What are the products when aqueous HCl reacts with solid KMnO₄?

We are able to add solid KMnO₄ grits to the aqueous HCl, and also we can add KMnO₄ grits to the water and make a KMnO₄ aqueous solution and react with HCl. When we react KMnO₄ with HCl, we are able to produce chlorine gas (Cl₂), potassium chloride (KCl), manganese chloride (MnCl₂) and water

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Due to formation of Mn²⁺ ions in the solution, the solution can be seen in light pink colour. A colourless solution is occurred due to the fewer concentration of Mn²⁺ ions.

KMnO₄ + HCl = KCl + MnCl₂ + H₂O + Cl₂

Above mentioned reaction is not a balanced chemical reaction. So, we need to balance this reaction and we will do it in next section.

How to balance KMnO₄ and HCl reaction?

This reaction is a redox reaction.

In this reaction, the oxidizing agent is KMnO₄. And the reducing agent is HCl. In KMnO₄, MnO₄^- is the oxidizing anion. In HCl, the reducing agent is Cl-.

In this KMnO₄ compound, the cataion is K⁺ and the anion is MnO₄^- . Oxidation number of the K⁺ ion is +1. So, the oxidation number of the anion is -1.

What is the oxidation number of the Mn ion in MnO₄^-?

MnO₄^- ion is reduced in to Mn²⁺ ion.

Let's calculate the oxidation number of the Mn ion in MnO₄^-. Let's assume as the oxidation number of the Mn is x, Most times, oxidation number of the oxygen is -2. We use algebraic method to calculate the oxidation number of manganese.

• x + (-2) * 4 = -1
• x + (-8) = -1
• x = -1 + 8
• x = 7

So, oxidation number of the Mn in MnO₄^-- is +7.

What is the oxidation number of the Cl₂ gas?

Chloride (Cl^-) anaion is oxidized in to chlorine gas (Cl₂). The charge of chlorine gas is 0. So the oxidation number of the chlorine atom in chlorine gas is 0.

How to balance the ionic reaction for KMnO₄ + HCl?

The difference of the oxidation of Cl^- to Cl₂ is +2. And the difference of reducing MnO₄^-- to Mn²⁺ is +5.

Now change the differences.

This is the balanced ionic reaction.

Balanced equation for KMnO₄ + HCl reaction

Safety during the KMnO4 and HCl reaction

Because HCl acid is a strong acid, it can cause injuries to skin and more. Therefore be careful when HCl solution is poured into the solution of KMnO₄. Also, be careful when aqueous HCl is prepared becaue HCl vapor can harl your lungs.

Also chlorine gas is a very toxic gas and inhaling chlorine gas can cause severe injuries. If you feel a chlorine gas odor, get away. This reaction should be done in a closed container to prevent release of chlorine gas to atmosphere.