15 Facts On HCl +CaO: With Several Elements Reaction

Hydrochloric acid and Calcium Oxide are inorganic compounds and can be presented as HCl & CaO respectively. Let us explore the various chemical reactions that take place.

Hydrochloric acid is also known as muriatic acid or simply Hydrogen chloride. The molecular weight of this strong acid is 36.458 g/mol. Calcium oxide is generally known as quicklime or burnt lime. Due to its basic nature, CaO reacts extensively with acids.

In this section, we will learn a few properties based on HCl + CaO reaction like the product formed, reaction enthalpy, conjugate pair, etc.

What Is The Product Of HCl and CaO  

Hydrochloric acid reacts with Calcium oxide to form calcium chloride and water.

  • HCl (l) + CaO (aq)  =  CaCl2 (aq) + H2O (l)

What Type Of Reaction Is HCl + CaO

The neutralization reaction takes place when Hydrochloric acid is added to Calcium oxide. HCl is a strong acid and CaO is a strong base. These two acid and base react with each other and neutralizes to form calcium chloride salt.

How To Balance HCl + CaO

A chemical equation can be balanced with the following steps.

Step-1: Write the elemental equation

The elemental equation is HCl (l) + CaO (aq)  =  CaCl2 (aq) + H2O (l)

Step-2: Write the number of atoms present on both the side of the chemical equation

Atoms present in LHSNumber of Atoms in LHSAtoms Present in RHSNumber of Atoms in RHS
Number Of Atoms Present In Reactant & Product

Step-3: Balance the number of atoms at both the side of the chemical equation

  • Here if we compare LHS and RHS, the number of the Hydrogen atom and Chlorine atoms seems to be unequal.
  • To balance the number of H and Cl-atoms in both LHS and RHS we need to multiply 2 with HCl in the left-hand side.

Step-4: Write the balance equation

2HCl (l) + CaO (aq)  =  CaCl2 (aq) + H2O (l)

HCl + CaO Titration

Apparatus and Chemical Reagent Required

  • 250 ml Conical Flask
  • Measuring Flask
  • 50 ml Burette
  • Pipette
  • Funnel
  • Burette Stand
  • Stirrer
  • Watch glass
  • Filter Paper
  • Distilled water
  • Calcium Oxide
  • Hydrochloric Acid


A phenolphthalein indicator is used to carry out this titration to indicate the endpoint with a physical change of the solution.


  • Calcium oxide is solid when it is added to water it forms Calcium hydroxide i.e Ca(OH)2.
  • Rinse the burette and fill it with M/10 Ca(OH)2 solution.
  • Pipette out 10cm3 of HCl solution and transfer it into a clean conical flask.
  • Add 2 drops of phenolphthalein indicator to the conical flask
  • Add M/10 Calcium hydroxide solution from the burette in a drop-by-drop manner to the conical flask with vigorous shaking of the flask until the colour changes to light pink.
  • Note down the final reading to find out the volume of calcium hydroxide used to neutralize the solution of Hydrochloric acid.
  • Repeat the experiment to get three concordant readings.
  • The readings can be recorded in the following table
Serial NumberInitial Burette ReadingFinal Burette ReadingVolume Of Ca(OH)2
1x cm3y cm3(y-x)cm3
2p cm3q cm3(q-p)cm3
3a cm3b cm3(b-a)cm3
Titration Table
  • Calculate the average volume i.e v ml of Calcium Hydroxide used during the reaction and use the value to find out the strength of Hydrochloric acid.
  • The strength of Hydrochloric acid can be calculated by using the formula [Ca(OH)2]M1V1 = [HCl] M2V2. Here M indicates concentration & V is the volume of the solution.

HCl + CaO Net Ionic Equation

  • Write the balanced chemical equation along with its physical state i.e. 2HCl (l) + CaO (aq)  =  CaCl2 (aq) + H2O (l)
  • Rewrite the balanced equation in ionic form i.e. 2H+(aq)+ 2Cl (aq) + CaO (aq)  =  Ca2+(aq)+ 2Cl (aq) + H2O (l)
  • The net ionic equation can be written by cancelling all the spectators i.e. 2H+(aq)+ CaO (aq)  =  Ca2+(aq)+ H2O (l)

HCl + CaO Conjugate Pairs

  • The conjugate base Hydrochloric acid is Cl ion.
  • The conjugate acid Calcium oxide is calcium hydroxide.

HCl And CaO Intermolecular Forces

The intermolecular force that exists between the H-Cl bond in HCl is dipole-dipole interaction due low electronegativity of the Cl-atom. As HCl is a polar molecule Vander Waal’s force of attraction also exists between the H-Cl bonds.

HCl And CaO Reaction Enthalpy

The standard reaction enthalpy of Hydrochloric acid and Calcium Oxide is -196.8 KJ/Mol.

Is HCl + CaO A Buffer Solution

The reaction of Hydrochloric acid with Calcium oxide is not a buffer solution as the reaction constitutes a strong acid and strong base.

Is HCl + CaO A Complete Reaction

The reaction between Hydrochloric acid and Calcium oxide is a complete reaction because the product formed during the reaction i.e CaCl2 is a salt that is neither acidic nor basic in nature.

Is HCl + CaO An Exothermic Reaction

The reaction between Hydrochloric acid & Calcium oxide is exothermic as its enthalpy change is negative.

Is HCl + CaO A Redox Reaction

The reaction of Hydrochloric acid with Calcium oxide is not a redox reaction because in this reaction both the reduction and oxidation are not taking place simultaneously. The only reduction reaction is taking place with an increase in the oxidation number of Cl from -1 to -2.

Is HCl + CaO A Precipitation Reaction

The reaction between Hydrochloric acid and Calcium oxide is not a precipitation reaction it is a neutralization reaction as the product Calcium chloride is a highly soluble salt.

Is HCl + CaO Irreversible Reaction

The reaction of Hydrochloric acid with Calcium oxide is an irreversible reaction as the reactants are completely consumed which is generally marked with a complete arrow.

Is HCl + CaO Displacement Reaction

 The reaction of Hydrochloric acid and Calcium Oxide is not a displacement reaction. It is a double replacement or double displacement reaction in which an exchange of ions takes place among the two reactants to form a new compound.


Hydrochloric acid and Calcium Oxide both are widely used as laboratory reagents. The product formed from this reaction i.e. Calcium Chloride is used in de-icing i.e. to prevent the formation of ice. It is also used in the production of activated charcoal.  

Arunima Chakraborty

Hello Everyone, I am Arunima Chakraborty. I have completed my MPhil in Chemistry from Christ University, Bangalore. I have 5.8 years of experience in curriculum designing & teaching. Currently, I am working as an SME with Lambda Geeks. Let's connect through LinkedIn:https://www.linkedin.com/in/arunima-chakraborty-87192a156

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