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

The reaction of strong acid (HCl) with lead (II) sulfide leads to the formation of solid cotunnite and a colorless chalcogen hydride gas. Let us find out in detail the reaction.

Muriatic acid or HCl is a strong colourless acid, prepared from hydrogen and chloride elements. Lead II sulfide (PbS) also referred to as Galena is a semiconducting material, the principal ore, and the most important compound of lead.

The following article studies the reaction mechanism, and type of reaction, in detail steps for balancing the reaction and calculates the reaction enthalpy and the net ionic equation.

What is the product of HCl and PbS?

The reaction of hydrochloric acid (HCl) with lead (II) sulfide (PbS)) forms lead (II) chloride and hydrogen sulfide.

PbS + 2HCl → PbCl₂ + H₂S

What type of reaction is HCl + PbS?

The reaction of HCl+PbS is classified as a neutralization reaction due to the formation of lead (II) chloride, which is a slightly soluble salt.

How to balance HCl + PbS?

A chemical reaction is balanced by following steps –

• The unbalanced chemical reaction is written down as:
• PbS + HCl → PbCl₂ + H₂S
• The number of moles of each compound on the reactant side and product side is tabulated down as:

• A reaction is balanced when the number of moles on the reactant side equals the number of moles on the product side. Here, moles of H₂ and Cl atoms are not equal on either side of the reaction.
• The given reaction is balanced by multiplying 2 with HCl on the reactant side
• The Balanced chemical reaction is –
• PbS + 2HCl → PbCl₂ + H₂S

HCl + PbS titration

There is no such titration performed between them, due to the absence of a base compound.

HCl + PbS net ionic equation

The net ionic equation is – PbS(s) + 2H⁺(aq) + 2Cl^–(aq) = PbCl₂(aq) + H₂S(g). The steps followed are as follows –

• The phase or state of each element is determined as shown below
• PbS(s) + 2HCl(aq) = PbCl₂(aq) + H₂S(g)
• The complete ionic equation is determined by separating all soluble ionic compounds into their respective ions – PbS(s) + 2H⁺(aq) + 2Cl^–(aq) = PbCl₂(aq) + H₂S(g)
• The ions present in both the reactant and product sides are removed.
• The net ionic equation includes only the species involved in the reaction.
• The net ionic equation is – PbS(s) + 2H⁺(aq) + 2Cl^–(aq) = PbCl₂(aq) + H₂S(g)

HCl + PbS conjugate pairs

The conjugate acid-base pair is not written in the case of PbS, while for HCl it is:

• The conjugate base of HCl= Cl^–

HCl and PbS intermolecular forces

The intermolecular forces acting on HCl and PbS are-

• London dispersion forces, Hydrogen bonding, and dipole-dipole interaction take place on HCl because it is a polar covalent compound.
• Hydrogen bond takes place in the case of PbS.

HCl + PbS reaction enthalpy

The reaction enthalpy is 76.45 KJ/mol, when HCl reacts with PbS. The number of moles and respective enthalpy of each compound present in the reaction is tabulated below. The reaction enthalpy is calculated as:

Reaction Enthalpy = [1*(-336) + 1*(-20.17)] – [1*(-98.32) + 2*(-167.15)] = 76.45 KJ/mol.

Is HCl + PbS a buffer solution?

HCL + PbS is not a buffer solution due to the presence of HCl which is a strong acid.

Is HCl + PbS a complete reaction?

HCl + PbS is a complete reaction since complete moles of reactant are consumed into the product at equilibrium.

Is HCl + PbS an exothermic or endothermic reaction?

HCl + PbS is an endothermic reaction since the enthalpy is +76.45 KJ/mol, decreasing the reaction temperature.

Is HCl + PbS a redox reaction?

HCl + PbS is not a redox reaction, since the oxidation state of elements remains unchanged during the reaction.

Is HCl + PbS a precipitation reaction?

HCl + PbS is a precipitate reaction due to the formation of precipitate PbCl₂ which is a slightly soluble salt.

Is HCl + PbS reversible or irreversible reaction?

HCl + PbS is a irreversible reaction and can be reversed only if there is a drastic change in pressure or temperature.

Is HCl + PbS displacement reaction?

HCl + PbS exhibits a double displacement (metathesis) reaction. In this reaction, hydrogen is traded with Sulphur atoms to form hydrogen sulfide (H₂S), and chlorine (Cl) is traded with lead (II) to lead (II) chloride (PbCL₂).

Conclusion

Hydrochloric acid reacts with lead (II) sulfide to form lead (II) chloride and hydrogen sulfide which has a variety of uses. PbCl₂ is used in the production of aurene glass, infrared transmitting glass, lead salts etc. H₂S is primarily used in the production of sulphuric acid and to create a variety of inorganic sulfides.