13 Facts on HBr + CaCO3: What, How to Balance & FAQs

In this reaction of HBr + CaCO₃, calcium carbonate is neutralized by hydrobromic acid. Let us learn more about this reaction.

Calcium carbonate is a calcium salt with the formula CaCO₃. It is a fertilizer, food coloring, and food-firming agent. Hydrogen bromide is a colorless gas, normally used as a catalyst, in the production of bromide compounds.

This article studies the various fact of HBr + CaCO₃ reactions like its enthalpy of reaction, reaction type, conjugate pairs, product, ionic equation, etc.

What is the product of HBr and CaCO₃?

CaCO₃ (calcium carbonate) combines with HBr (hydrobromic acid), results in the formation of H₂O (water), CO₂ (carbon dioxide), and CaBr₂ (Calcium bromide).

HBr + CaCO₃ → CaBr₂ + H₂O + CO₂

What type of reaction is HBr + CaCO₃ 

It is an Exothermic Reaction and neutralization reaction since, formation of CaBr₂ takes place which is a neutral salt.

How to balance HBr + CaCO₃

The unbalanced equation of HBr + CaCO₃ reaction is given by,

HBr + CaCO₃ → CaBr₂ + H₂O + CO₂

• In this case, we have two bromine and two hydrogens on the product side and one each one of them on the reactant side. 
• Therefore, we have to change the stoichiometry for HBr into two.
• Balanced Equation: 2HBr + CaCO₃ → CaBr₂ + H₂O + CO₂

HBr + CaCO₃ conjugate pairs

HBr + CaCO₃ reaction has the following conjugate pairs,

• Br- is the conjugate base of HBr because that is what HBr becomes after losing its H+ cation.
• Conjugate acid-base pair for CaCO₃ is not possible.

HBr + CaCO₃ net ionic equation

• Net ionic equation:
• CaCO₃ (s) + 2H⁺ (aq) →. Ca²⁺ (aq) + CO₂ (g) + H₂O (l)

The net ionic equation for CaCO₃ + HBr = CaBr₂ + CO₂ + H₂O is written in three steps:

• Beginning with balancing the molecular equation.
• 2HBr + CaCO₃ → CaBr₂ + H₂O + CO₂
• Secondly, write the states and separate the soluble ionic compounds into their ions (these are the strong electrolytes denoted by an (aq)). Complete ionic equation:
• CaCO₃ (s) + 2H⁺ (aq) + 2Br^– (aq) → Ca²+ (aq) + 2Br^– (aq) + CO₂ (g) + H₂O (l)
• Finally, any spectator ions are removed. These ions can be found on both sides of the ionic equation. 

HBr and CaCO₃ intermolecular forces

The forces between HBr and CaCO₃ are as follows:
• Forces acting on HBr include permanent dipole-dipole, dispersion forces and hydrogen bonding.
• In the molecules of CaCO₃, there is an electrostatic attraction.

HBr + CaCO₃ reaction enthalpy

HBr + CaCO₃ exhibits a reaction enthalpy of -25.67 kJ.

• The following is a table of the reaction enthalpies of formation of each component on either side of the reaction:

Compound	Moles	Enthalpies
CaCO3(aq)	1 mol	-1219.97kJ/mol
HBr(g)	2 mol	–36.23 kJ/mol
CaBr2(s)	1 mol	-682.8 kJ/mol
CO2(g)	1 mol	-393.5 kJ/mol
H2O(g)	1 mol	-241.8 kJ/mol

• Change in reaction enthalpy = Sum of enthalpies in product side – sum of enthalpies in reactant side.
• Enthalpy change = (-1219.97-36.23) – (-682.8-393.5-241.8) = -25.67 kJ/mol.

Is HBr + CaCO₃ a buffer solution

HBr + CaCO₃ is not a buffer solution because HBr is a strong acid since its pKa value is -9. Calcium carbonate is a salt that is both a strong base due to the presence of the calcium ion and weak acid because of the presence of the carbonate ion and is typically derived from carbonic acid. 

Is HBr + CaCO₃ a complete reaction

HBr + CaCO₃ is a complete reaction because all the products formed are stable.

Is HBr + CaCO₃ an exothermic or endothermic reaction

HBr + CaCO₃ is exothermic since,  ΣΔH°f(reactants) > ΣΔH°f(products).

Is HBr+ CaCO₃ a redox reaction

HBr + CaCO₃ is not a redox reaction, because oxidation and reduction reactions do not occur concurrently in the process,

Is HBr + CaCO₃ a precipitation reaction

HBr + CaCO₃ is not a precipitation reaction, CaBr₂ is not a salt.

Is HBr + CaCO₃ reversible or irreversible reaction

HBr + CaCO₃ is irreversible reaction because the products do not revert to the original reactant at constant operating conditions.

Is HBr + CaCO₃ displacement reaction

HBr + CaCO₃ is not a displacement reaction since formation of new compound takes place without exchange of ions.

Conclusion

Reaction of hydrogen bromide with calcium carbonate involves formation of neutral salt, CaBr₂, gas and liquid water. CaBr₂ is used as dense aqueous solutions in drilling fluids, used as food preservatives and in photography. CO₂ is a crucial industrial material used as inert gas in pressurizing gas in oil refinery.