15 Facts on HCl + Sb2S3: What, How To Balance & FAQs

Antimony trisulphide(Sb2S3) is also known as stibnite and it is a water insoluble compound. HCl is alkaline agent. Let us study briefly about HCl and Sb2S3 compounds.

Antimony trisulphide is a solid, dark gray-black color, odorless  compound. It is covalently bonded and it has a resonating structure. This is naturally occurring compound and ionic in nature. Hydrochloric acid has a pungent smell, colorless and it is soluble in water and ethanol,after heating it emits toxic fumes.

In this article we are going to discuss some properties such as displacement reaction, enthalpy, precipitation reaction,titration etc.

What is the product of HCl+Sb2S3 ?

HCl+Sb2S3 forms antimony trichloride (SbCl3) and hydrogen sulfide gas(H2S).

 Sb2S3 + 6HCl  → 2 SbCl3  + 3H2S

What type of reaction is HCl + Sb2S3 ?

HCl + Sb2S3 is a double displacement reaction.

How to balance HCl + Sb2S3 ?

The unbalanced reaction of HCl + Sb2S3 is written below-

Sb2S3 + HCl  → SbCl3 + H2S

For balancing this reaction we should follow these steps-

  • In this reaction the Sb atom is not equal on both reactant and product side of the equation.
  • In the reactant side it is 2 and the product side it is 1, respectively
  • Sb2S3 + HCl  → SbCl3 + H2
  • For balancing this we will multiplied it on the product side by 2 and the reaction will become as
  • Sb2S3+ HCl  → 2Sb2Cl3  + H2S
  • But the Cl atom is unbalanced now, so in the reactant side we will multiplied HCl by 6.
  • Sb2S3 + 6HCl  → 2Sb2S3 + H2S
  • Now, the number of H atoms is unbalanced on the product side so we will multiply it by 3.
  • Thus, we get our balanced reaction for HCl+Sb2S3.
  • Sb2S3 + 6HCl  → 2Sb2S3 + 3H2S

HCl + Sb2S3 titration ?

To estimate the amount of the salt Sb2S3 by HCl, we have to do titration.


  • Burette
  • Pipette
  • Beaker
  • Conical flask
  • Volumetric flask


In this titration phenolphthalein is used as a pH indicator.


  • Firstly weigh the unknown sample and take into the conical flask
  •  In this sample add 100 ml water and heat for 10 to 15 min and  swirl it continuously.
  • The sample is showing reddish color then it confirms that antimony trisulphide is present.
  • And heat it until the H2S gas is not removed from this sample. Add the concentrated HCl in this sample.
  • Now add phenolphthalein as an indicator into the sample. 
  • The color of this sample becomes pink and slowly it will disappear and the end point will occur.
  • HCl is used as a titrant whose concentration is known.
  • Sb2S3 is used as a titre whose concentration is unknown.
  • The concentration of this solution is calculated m1v1 = m2v2.

HCl + Sb2S3 net ionic equation ?

The net ionic equation of HCl + Sb2S3 is written below-

Sb2S3(s) + 6H+(aq) + 6Cl(aq)  → 2Sb+3(aq) + 6Cl(aq) + 3H2S(g)

Follow the below mentioned steps to get net ionic equation-

  • The complete ionic equation is written as follows
  • Sb+3(s) + S-2(s)  + 6H+(aq) + 6Cl(aq)  → 2Sb+3(aq) + 6Cl(aq) + H+(g) + S-2(g)
  • In this equation Cl is a spectator ion that is removed from both reactant and product sides.
  • After removing the spectator ions, we get our net ionic reaction.
  • Thus, the net ionic equation is written below-
  • Sb2S3(s) + 6H+(aq)  → 2Sb+3(aq) + 3H2S(g)

HCl + Sb2S3 conjugate pairs ?

In this reaction of HCl + Sb2S3 the available conjugated pairs are as follows-

  • Conjugate pair of H2S = HS
  • Conjugate pair of HCl  = Cl

HCl and Sb2S3 intermolecular forces ?

HCl + Sb2S3 has following intermolecular forces

  • HCl contains dipole dipole interaction because of the interaction of opposite charges. Induced dipole – induced dipole force also exists in this molecule.
  • Sb2S3 contains covalant bond due to strong packaging in ions.

HCl + Sb2S3 reaction enthalpy ?

The reaction enthalpy of HCl+Sb2S3 is -336.7KJ/mol. This is calculated using this formula and values that is written below-

CompoundsEnthalpy of formation(∆H)in KJ/mol
Enthalpy formation values for compounds
  • (∆H) = ΣΔHf°(products) – ΣΔHf° (reactants)  
  • (∆H) = [(-1578)+6(-167.1)-2(-381.2)+3(-20.6)] KJ/mol
  • (∆H)=-336.7 KJ/mol

Is HCl + Sb2S3 a buffer solution ?

HCl+Sb2S3 reaction is not suitable for buffer solution because HCl is a strong acid which does not participate in buffer solution.

Is HCl + Sb2S3 a complete reaction ?

HCl+Sb2S3 reaction is a complete reaction because it gives two major products- antimony trichloride (SbCl3) which is acidic in nature and Hydrogen sulfide (H2S) is released as gas, so no further reaction is possible.

Is HCl+ Sb2S3 an exothermic or endothermic reaction ?

HCl+Sb2S3 reaction is exothermic in nature according to the thermodynamics law of conservation of energy, where the overall enthalpy is negative (-336.7 kJ/mol) and heat is released.

graph 2 2 edited 1
Exothermic reaction

Is HCl+ Sb2S3 a redox reaction ?

HCl+Sb2S3 reaction is not a redox reaction because both the reactant and the product side oxidation states are similar and atoms are not changing their oxidation state.

Is HCl + Sb2S3 a precipitation reaction ?

HCl+Sb2S3 reaction is not a precipitation reaction because the product SbCl3 is soluble in water.

Is HCl + Sb2S3 reversible or irreversible reaction ?

HCl + Sb2S3 reaction is an irreversible reaction because the nature of the product antimony trichloride (Sb2Cl3) is acidic and this type of product gives forward direction reactions due to shifting of equilibrium.

Is HCl + Sb2S3 displacement reaction ?

HCl+Sb2S3 reaction is a type of double displacement reaction because in this reaction the Sb+2 ion is displaced by the H+ ion from the HCl and the S-2 is displaced from Sb2S3.

Sb2S3 + 6HCl  → 2 SbCl3  + 3H2S


The above article defines the reaction between Sb2S3 + HCl gives a lewis acid antimony trichloride (Sb2Cl3) with the sulphuric acid (H2SO4). Antimony trisulfide has various uses in industries such as glass formation, painting, also used as starting materials in antimony compounds.