15 Facts on HCl + MnO: What, How To Balance & FAQs

The temperature of the flask increases when HCl is mixed with MnO. Let us have a look into the chemical reaction of both in the following article.

HCl + MnO can be considered an acid-base reaction. Here,Hydrochloric acid is an inorganic acid that easily dissociates to give hydronium ions (H3O+) and chloride (Cl) in an aqueous medium, whereas Manganese(II)oxide is a basic metal oxide.

In this article, we will learn about balancing chemical reactions and products formed when they react with each other.

What is the product of HCl and MnO?

HCl and MnO react together to form manganese dichloride (MnCl2) and H2O.

HCl  + MnO = MnCl2 + H2O

What type of reaction is HCl + MnO?

The mixture of HCl + MnO is a neutralization reaction, which results in the formation of manganese dichloride salt and water.

How to balance HCl + MnO?

The HCl + MnO reaction is balanced as per the Law of Conservation of Mass using the following steps.

  • Step1: First, write the chemical formula of the reactant and the product.
  • HCl + MnO = MnCl2 + H2O
  • Step2: Count the number of atoms for each type in reactant and product. If they are different, then we need to balance the atoms. Keeping in mind the stoichiometry, multiply HCl by 2.
  • 2HCl   + MnO  = MnCl2 + H2O
  • Step3: This is the balanced chemical equation in which HCl, MnO, MnCl2, and H2O have a stoichiometry of 2, 1, 1, 1, respectively.

HCl + MnO titration

HCl + MnO follows acid-base titration in which MnO forms the standard solution by which HCl is titrated.


Methyl orange


Burette, Pipette, Conical flask, Burette stand, Funnel, Stirrer, White glazed tile, Measuring flask, Hydrochloric acid, Manganese(II)oxide, Methyl orange.


  • First wash and rinse the burette with M/10 MnO solution.
  • Note the initial reading.
  • Pipette out 10 ml of HCl solution with the help of a pipette and transfer it into a conical flask.
  • Add 2 drops of methyl orange which act as indicator into the conical/titration flask.
  • Add M/10 manganese oxide solution to the titration flask till the color changes to light pink.
  • Note the final reading and determine the volume of the manganese oxide solution used to neutralize the HCl solution.
  • The experiment need to be repeated till you get concordant readings.

HCl + MnO net ionic equation

The net ionic equation is written when all the species dissociate into ions. Using the balanced chemical reaction, the ionic equation is written as:

2H+(aq) + 2Cl(aq) + Mn2+(aq) + O2-(aq)   =   Mn2+(aq) + 2Cl(aq) + H+(aq) + OH(aq)

HCl + MnO conjugate pairs

HCl + MnO forms the conjugate acid-base pairs.

  • The conjugate base of HCl and H2O is Cl and OH, respectively.

HCl and MnO intermolecular forces

Both HCl and MnO show the dipole-dipole intermolecular force of attraction as they have permanent dipole moments because of the electronegativity difference.

HCl + MnO reaction enthalpy

The enthalpy of reaction is -289.8 kJmol-1. Using  enthalpy of the formation of HCl, MnO, MnCl2, and H2O reaction enthalpy can be calulated and tabulated as follows.

S.No. Chemical Compound Standard enthalpy of formation (Hform) (kJmol-1)
1 HCl 92.3
2 MnO -384.9
3 MnCl2 -481.2
4 H2O -285.8
Standard enthalpy of formation

 = (-481.2-285.8+92.3+384.9)kJmol-1

-289.8 kJmol-1

Is HCl + MnO a buffer solution?

A mixture of HCl + MnO is not a buffer solution because HCl is a strong acid, and thus it does not fulfil the requirement of a buffer solutionm.

Is HCl + MnO a complete reaction?

The mixture of HCl with MnO is a complete reaction because HCl completely reacts with MnO to form MnCl2 and water.

Is HCl + MnO an exothermic or endothermic reaction?

The chemical reaction of HCl and MnO is exothermic as the calculated standard enthalpy of the reaction of HCl and MnO comes out to be negative.

Is HCl + MnO a redox reaction?

The chemical reaction between HCl and MnO cannot be termed as redox reaction because the oxidation state of all the elements remains the same in both reactants and the product. 

Is HCl + MnO a precipitation reaction?

The chemical reaction between HCl and MnO is not a precipitation reaction. The MnCl2 formed does not precipitate out because it does not have a high ionic character which can be observed by the Fajan rule.

Is HCl + MnO reversible or irreversible reaction?

The HCl + MnO reaction is not reversible because the stable ionic compound MnCl2 is formed at a constant temperature, pressure, and concentration.

Is HCl + MnO displacement reaction?

A double displacement reaction is observed in the balanced chemical reaction of HCl and MnO.


The reaction of hydrochloric acid with manganese oxide produces manganese chloride and water. The oxidation state of Mn remains unchanged. This is an example of neutralization reaction.