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

Hydrogen bromide (HBr) is a colorless inorganic gas and Lead sulfide (PbS) is an inorganic compound. Let us see what happens when these two compounds react.

HBr produces hydrobromic acid, stronger than hydrochloric acid (HCl) when dissolved in water. And thus, HBr is highly dissociated in its aqueous solution. HBr is highly corrosive, and it readily fumes in the air. At the same time, Lead sulfide (PbS) is a silvery black powder.

This article will focus on these two compounds’ reactions and their properties.

What is the product of HBr and PbS?

Hydrogen sulfide (H2S) and lead bromide (PbBr2) are the resulting products in HBr + PbS reaction.

HBr+PbS = PbBr2+H2S

What type of reaction is HBr + PbS?

HBr + PbS reaction is an example of a double displacement reaction.

How to balance HBr + PbS?

HBr + PbS reaction is balanced using the hit-and-trial method. The steps in balancing are given below:

  • HBr + PbS = PbBr2+H2S
  • The number of hydrogen atom is one in the reactant and two in the product. Multiply HBr by 2 to make the number of H atoms on both sides of the reaction equal.
  • 2HBr + PbS = PbBr2+H2S
  • Now, the number of hydrogen, bromine, lead and sulfide on both sides are 2, 2, 1 and 1, respectively. Thus, the reaction is now balanced.

HBr + PbS titration

HBr + PbS titration is not practically possible. Because the neutralization reaction is not taking place here and thus endpoint determination by pH change will not be possible.

HBr + PbS net ionic equation

2H+ (aq) + 2Br (aq) + PbS (s) = PbBr2 (s) + H2S (g)

In HBr + PbS reaction, HBr is in aqueous state and is dissociated. The ionic equation of a reaction contains all the ions in dissociated form. The net ionic equation for the reaction between HBr and PbS is given above:

HBr + PbS conjugate pairs

In HBr + PbS reaction has the following conjugate acid-base pair.

  • The conjugate base of HBr is Br.
  • HBr=H+ + Br

HBr and PbS intermolecular forces

HBr + PbS reaction has the following intermolecular forces,

  • HBr is a polar molecule due to electronegativity differences between H and Br.
  • The bonding interaction in HBr is covalent.
  • PbS is an ionic compound with Pb2+ and S2- ions. This result in dipole-ion interactions between H-Br and Pb-S.
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Intermolecular interactions between HBr and PbS

HBr + PbS reaction enthalpy

For HBr + PbS reaction, the enthalpy data is -27.27 KJ/mol.

  • Enthalpy of formation of HBr, H1= -83.68 KJ/mol
  • Enthalpy of formation of PbS, H2= -102.93 KJ/mol
  • Enthalpy of formation of H2S, H3= -20.17 KJ/mol
  • Enthalpy of formation of PbBr2, H4=-277.39KJ/mol
  • The reaction enthalpy for; 2HBr + PbS = PbBr2+H2S , is given by;
  • Hr = [H4+ H3]-[2H1+ H2] = [-277.39+-20.17]-[2×-83.68+-102.93] = -27.27 KJ/mol

Is HBr + PbS a buffer solution?

HBr + PbS system is not a buffer solution. Because HBr is highly acidic and PbS dissolves in water to give PbSO4, a weak electrolyte.

Is HBr + PbS a complete reaction?

HBr + PbS reaction is a complete reaction. Because, two molecules of HBr and one mole PbS react to produce one mole H2S and one mole PbBr2.

Is HBr + PbS an exothermic or endothermic reaction?

HBr + PbS reaction is an exothermic reaction. Because, in HBr + PbS reaction, an amount of heat (-27.27 KJ/mol) is liberated.

Is HBr + PbS a redox reaction?

HBr + PbS reaction is not a redox reaction as the oxidation state of each species is the same in reactant and product.

Is HBr + PbS a precipitation reaction?

HBr + PbS reaction is not a precipitation reaction as the PbS reactant is in a solid state.

Is HBr + PbS reversible or irreversible reaction?

HBr + PbS reaction is an irreversible reaction as the energy change is not small.

Is HBr + PbS displacement reaction?

HBr + PbS reaction is a displacement reaction. Here sulfide and bromide ions are displaced simultaneously.

Conclusion

The reaction between Hydrobromic acid (HBr) and lead sulfide (PbS) is a double displacement reaction. As a result of this reaction, a white-colored powder of lead bromide (PbBr2) and colorless gas with a strong smell (H2S) is formed.