15 Facts on HCl + MgO2: What, How To Balance & FAQs

HCl is a strong acid that reacts with an oxidizing agent MgO2 giving multiple products. Let us discuss the reaction: HCl + MgO2.

Hydrochloric acid (HCl) is a pungent, colourless liquid, and has fumes in air when concentrated. Magnesium peroxide (MgO2) is a white, odourless fine powder which releases oxygen by breaking down with water at a controlled rate. It is used in the agricultural and environmental industries widely.

In the following article, we are going to discuss about various properties of the reaction like,  the type of reaction, how to balance the reaction, reaction enthalpy, conjugate pair, net ionic equation,etc. for the reaction between HCl and MgO2.

What is the product of HCl + MgO2?

Magnesium chloride (MgCl2), water (H2O) and chlorine gas (Cl2) are produced in the reaction between HCl and MgO2.

HCl + MgO2 = MgCl2 + Cl2 + H2O

What type of reaction is HCl + MgO2?

HCl + MgO2 is a redox reaction where oxidation of Cl and reduction of oxygen occurs.

How to balance HCl + MgO2?

The reaction HCl + MgO2 = MgCl2 + Cl2 + H2O is not yet balanced.

The above equation is balanced using this method:

  • The reactants and the products are labeled with different variables to represent the unknown coefficients e.g, a, b, c, d and e.
  • aHCl + bMgO2 = cMgCl2 + dCl2 + eH2O
  • The coefficients are equated after arranging the same type of element together .
  • Then we rearrange these  by their stoichiometric proportion individuallys, we get
  • H=a=2e; Cl=a=2c=2d; Mg=b=c; O=2b=e
  • The values of the coefficients are calculated using Gaussian elimination method.
  • Thus , We get the values :
  • a=4 , b=1 , c=1 , d=1, e=2
  • Hence  the overall balanced equation is:
  • 4HCl + MgO2 = MgCl2 + Cl2 + 2H2O

HCl + MgO2 titration

The titration of HCl and MgO2  is a strong acid-base titration in which HCl is a strong acid and MgO2  is a strong base. The process of titration is mentioned below:

Apparatus Used

  • Burette
  • Pipette
  • Conical flask
  • Volumetric flask
  • Glass rod

Indicator

  • Phenolphthalein is used as indicator, which turns pink in basic medium and remains colourless in acidic medium.

Procedure

  • Magnesium peroxide is not very soluble in water and henc direct titration is very difficult. Thus back titration method is used.
  • Two solutions of HCl and NaOH are prepared of known concentration
  • Then the burette is filled with the prepared NaOH solution.
  • Then an unknown amount of magnesium peroxide was completely dissolved in excess amount of prepared hydrochloric acid  in a conical flask.
  • Two drops of Phenolphthalein is added to the HCl solution in the conical flask and then the titration is performed by adding NaOH dropwise from the burette in the conical flask and then the end point is recorded.
  • The excess HCl present in the flask is calculated from the amount of NaOH used using the formula given below:
  • VHClSHCl=VNaOHSNaOH .

HCl + MgO2 net ionic equation

The net ionic equation for the reaction HCl + MgO2 is –

2H+(aq) + 3Cl(aq) + MgO2(s) = Mg2+(aq) + Cl2(g) + 2OH(aq)

The net ionic equation is derived by following these steps –

  • First step is to mention the chemical states of the compounds in the equation:
  • 4HCl(aq.) + MgO2(s)= MgCl2(aq.)  + Cl2(g) + 2H2O(aq.)
  • Then the corresponding compounds are split into their ionic forms as follows
  • 4H+(aq) + 4Cl(aq) + MgO2(s) = Mg2+(aq)+ Cl(aq) + Cl2(g) + 2H+(aq)+ 2OH(aq)
  • Then the common ions on each sides are eliminated .
  • Hence the net ionic equation is:
  • 2H+(aq) + 3Cl(aq) + MgO2(s) = Mg2+(aq) + Cl2(g) + 2OH(aq)

HCl + MgO2 conjugate pairs

The conjugate pairs of HCl + MgO2 are:

  • Cl–  is the conjugate base of HCl .
  • MgO2 does not have any conjugate acid because it does have any proton.

HCl + MgO2 intermolecular forces

London force and dipole dipole interaction are the intermolecular forces present in both HCl and MgO2 molecules.

HCl + MgO2 reaction enthalpy

HCl + MgO2 reaction enthalpy is -391.58 KJ/mol.

MOLECULEENTHALPY (KJ/MOL)
HCl-92.3
MgO2-489.2
MgCl2-800
Cl2121.68
H2O-285.83
Table for enthalpy
  • The formula for enthalpy calculation is = Enthalpy of Product – Enthalpy of Reactant
  • = [-800+121.68-(2×285.83)] [-489.2-(4×92.3)]
  • = -1249.93+858.4 KJ/mol
  • = -391.58 KJ/mol

Is HCl + MgO2 a buffer solution?

HCl + MgO2 does not form a buffer solution because of the fact that HCl is a strong acid and hence it cannot form a buffer solution.

Is HCl + MgO2 a complete reaction?

HCl + MgO2 is a complete reaction because at the end of the reaction Magnesium chloride, water and chlorine gas are obtained as products.

Is  HCl + MgO2 an exothermic or endothermic reaction?

HCl + MgO2 is an exothermic reaction since we get a negative value of enthalpy (-391.58 KJ/mol) at the end of the reaction.

Is HCl + MgO2 a redox reaction?

HCl + MgO2 is a redox reaction where HCl is a reducing agent and MgO2 is an oxidizing agent. In this reaction oxidation of Cl and reduction of oxygen occurs.

Is HCl + MgO2 a precipitation reaction?

HCl + MgO2 is not a precipitation reaction since we do not get any precipate at the end of the reaction.

Is HCl + MgO2 reversible or irreversible reaction?

HCl + MgO2 is an irreversible reaction because the products formed– Magnesium chloride, water and chlorine gas cannot react back and form the initial reactants.

Is HCl + MgO2 displacement reaction?

HCl + MgO2 is a displacement reaction. In the above reaction O is replaced by Cl to form MgCl2 salt along with chlorine gas and water as the product.

d1
Displacement reaction

Conclusion

Magnesium peroxide, a fine white powdered substance reacts with strong hydrochloric acid via displacement reaction to form a white crystalline salt magnesium chloride, water along with fumes of chlorine gas having a pungent odour.