15 Facts on HBr + Na2S: What, How To Balance & FAQs

Hydrogen bromide is a common chemical reagent used in analytical reactions to form industrially important compounds. Let us explore the chemical reactivity of HBr and Na₂S.

HBr is a reagent used in the laboratory synthesis of organo-bromine compounds via free radical addition. The compounds are thus strong alkylating agents. Na₂S is generally found as pure crystalline colorless solid that smells like a rotten egg.

The reactivity of HBr and Na₂S produces oxygen scavenger molecules utilised in water purification or as bleaching agents in paper and pulp industry. Thus, important reactivity conditions of the reactants are discussed as follows.

What is the product of HBr and Na₂S?

HBr and Na₂S interact to produce hydrogen sulfide and sodium bromide. The complete reaction is given as:

HBr + Na₂S = NaBr + H₂S

What type of reaction is HBr + Na₂S?

HBr + Na₂S is an acid-base reaction where HBr is a Bronsted acid and Na₂S is a Bronsted base that reacts to produce an ionic salt NaBr.

How to balance HBr + Na₂S?

The algebraic methodology given below is followed to balance the chemical reaction

Na₂S + HBr = NaBr + H₂S,

• Each species present in the equation is marked with a respective variable (A, B, C, and D) to illustrate unknown coefficients.
• A Na₂S + B HBr = C NaBr + D H₂S
• Then, a suitable quantity, the coefficient of reactants and product species, is applied to solve the equation.
• Na = 2A = C, S = A = D, H = B = 2D, Br = B = C
• The Gaussian elimination methodology is applied to ascertain all the variables and coefficients, and the outcomes are
• A = 1, B = 2, C = 2, and D = 1
• Hence, the overall balanced equation is,
• Na₂S + 2HBr = 2 NaBr + H₂S

HBr + Na₂S titration

HBr + Na₂S titration system is not possible as Na₂S is a Bronsted base which cannot perform acid-base titration along with HBr.

HBr + Na₂S net ionic equation

The net ionic equation of HBr + Na₂S is

 2 H⁺ (aq) + Na₂S (s) = 2 Na⁺²  (aq) + H₂S (g)

The net ionic equation is obtained using the following steps

• Write the balanced chemical equation and designate the physical states of reactants and products accordingly

• 2 HBr + Na₂S = 2 NaBr + H₂S
• Now, strong acids, bases, and salts dissociate into ions whereas pure solid substances and molecules do not dissociate
• Thus, the net ionic equation is
• 2 H⁺ (aq) + Na₂S (s) = 2 Na⁺² (aq) + H₂S (g)

HBr + Na₂S conjugate pairs

• Conjugate pair of acid HBr is Br^–.
• Conjugate pair of base Na₂S is Na₂⁺.

HBr and Na₂S intermolecular forces

Intermolecular forces acting on HBr and Na₂S are:

• HBr molecules form dipole-dipole interaction and London dispersion forces among the molecules.
• Na₂S forms strong ionic bonding between Na and S molecules.

HBr + Na₂S reaction enthalpy

HBr + Na₂S exhibits a reaction enthalpy of -274.8 kJ/mol.

Is HBr + Na₂S a buffer solution?

HBr + Na₂S cannot form a buffer because HBr is not a weak acid and Na₂S is not a salt of any conjugate base of weak acid.

Is HBr + Na₂S a complete reaction?

HBr + Na₂S is a complete reaction because the stable products (NaBr and H₂S) are formed in the reaction.   

Is HBr + Na₂S an exothermic or endothermic reaction?

HBr + Na₂S is an exothermic reaction because the formation of an ionic compound, NaBr releases heat thus, the enthalpy of the reaction is negative in value.

Is HBr + Na₂S a redox reaction?

HBr + Na₂S is not a redox reaction because oxidation and reduction reactions do not occur simultaneously in the process. The oxidation state of Na, S, Cl, and H remains +1 on both the reactant and product sides.

HBr + Na₂S a precipitation reaction?

HBr + Na₂S is not a precipitation reaction because the salt formed in the reaction solubilizes in HBr.

Is HBr + Na₂S reversible or irreversible reaction?

HBr + Na₂S is an irreversible reaction because the products do not change back into the original reactants when the conditions of the reactions are kept unchanged.

Is HBr + Na₂S displacement reaction?

HBr + Na₂S is a double displacement reaction because both the anion component of the reactants (Br and S ) is displaced with the respective cationic part (H and Na) to form new combination products.

Conclusions

The chemical reactivity of HBr + Na₂S forming an ionic salt, NaBr is a double displacement exothermic combination reaction. NaBr is a crystalline solid which crystallizes in a cubic crystal lattice similar to NaCl. NaBr functions as a source of bromide in numerous organic synthesis reactions.

Avneesh Rawat

Hi…..This is Avneesh Rawat, I have done my Ph.D. in Chemistry from Govind Ballabh Pant University of Agriculture and Technology. Currently, I am working as Project Associate in CSIR, CIMAP, Pantnagar. I am specializing in handling sophisticated GC/MS, GC, HPLC, FTIR instrumentation.