15 Facts on H2SO3 + Zn(OH)2: What, How To Balance & FAQs

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Zinc hydroxide and sulphurous acid are inorganic compounds with chemical formulas, Zn(OH)2 and H2SO3 respectively. Let us explore more about the reaction between H2SO3 and Zn(OH)2.

H2SO3 is a liquid, used as reducing agents and as disinfectants. H2SO3 is a weak acid. H2SO3 give two H+ ions. The molecular mass of H2SO3 is 82 g/mol. Its pka value is 1.12. Molecular mass of Zinc hydroxide is 99g/mol.

In this article, we will learn about a few properties on the reaction between H2SO3 and Zn(OH)2 such as the type of reaction, the product formed, buffer solution, conjugate pairs, type of intermolecular forces and many other related facts.

What is the product of Zn(OH)2 and H2SO3 ?

Zinc sulphite(ZnSO3) and water(H2O) are formed when Zn(OH)2 reacts with H2SO3.

H2SO3 + Zn(OH)2 ———-> ZnSO3 + 2H2O.

What type of reaction is H2SO3 + Zn(OH)2?

The reaction between H2SO3 + Zn(OH)2 is classified as an acid-base reaction, as an acid neutralizes a base to produce salt and water.

How to balance H2SO3 + Zn(OH)2 ?

The equation for the reaction between H2SO3 and Zn(OH)2 is balanced using the following steps.

  • The general equation of H2SO3 + Zn(OH)2 reaction is,
    H2SO3 + Zn(OH)2———-> ZnSO3 + 2H2O
  • Calculate the number of moles of each element involved in both the reactant and product side of the reaction.
ElementsReactant (LHS)Product (RHS)
Zn11
O55
H44
S11
Number of moles on Left hand side and Right hand side of the reaction.
  • Thus the reaction is self balanced and the overall balanced reaction is given by,
    H2SO3 + Zn(OH)2 = ZnSO3 + 2H2O
  • The number of moles of elements(H,O,S,Zn) present on reactant side is equal to the moles on the elements(H,O,S,Zn) present on product side.
  • Thus the reaction is self balanced and the overall balanced reaction is given by –
    H2SO3 + Zn(OH)2 = ZnSO3 + 2H2O

H2SO3 + Zn(OH)2 titration?

An acid-base titration between H2SO3 and Zn(OH)2 can be performed to estimate the strength of sulphurous acid. The procedure for titration is as follows –

Apparatus

  • Burette
  • Burette holder
  • Pipette,
  • Distilled water,
  • Conical flask,
  • Volumetric flask,
  • Wash bottle,
  • Stirrer
  • Beakers.

Indicator

  • Here we use the Phenolphthalein indicator. It is a acid-base indicator used to find out the end point of the titration.

Procedure

  • 0.1 N freshly prepared Zn(OH)2 is taken in the burette.
  • 10 ml of H2SO3 is pipetted out into a clean conical flask.
  • Add 1-2 drops of phenolphthalein indicator.
  • Add Zn(OH)2 dropwise from the burette into the conical flask with constant stirring until the appearance of light pink color. This is the end point of titration.
  • Note the volume of Zn(OH)2 required to neutralize the sulphurous acid solution.
  • The above procedure is repeated for 3 consistent readings.
  • The strength of NZn(OH)2 VZn(OH)2= NH2SO3 VH2SO3

H2SO3 + Zn(OH)2 net ionic equation ?

  • The net ionic equation between H2SO3 + CaO is,
    H2SO3(aq) + Zn2+ (aq) + (OH-)(aq) = CaSO3(s)+ H2O (l)

The listed down steps are used to derive the net ionic equation:

  • Write the balanced molecular equation along with the physical state.
    H2SO3(aq) + Zn(OH)2(aq) = ZnSO3(s)+2H2O(l)
  • Now, write the ionic form of each of the substances existing in aqueous form and capable of complete dissociation in water. H2SO3 is a weak electrolyte that does not completely dissociate into ions in aqueous form. Hence, the complete ionic equation is,
    H2SO3(aq) + Zn2+ (aq) + 2(OH–)(aq) = ZnSO3(s) + 2H2O (l)
  • We found that the complete ionic equation is identical to the net ionic equation. Thus the net ionic equation is,
    H2SO3(aq) + Zn2+(aq) + 2(OH–)(aq) = ZnSO3(s)+ 2H2O(l)

H2SO3 + Zn(OH)2 conjugate pairs ?

H2SO3 have HSO3– as the conjugate-base. Conjugate acid of Zinc hydroxide is ZN(OH)3–.

H2SO3 and Zn(OH)2 intermolecular forces?

  • In H2SO3, London dispersion forces, Van der Waals forces, and dipole-dipole interactions are the intermolecular forces that bind the hydrogen and sulphite ions together.
  • In Zn(OH)2, there are coulombic forces as well as covalent interaction present in the molecule.

H2SO3 + Zn(OH)2 reaction enthalpy ?

The standard reaction enthalpy of the reaction between H2SO3 and Zn(OH)2 is negative.

Is H2SO3 +Zn(OH)2 a buffer solution ?

H2SO3 + Zn(OH)2 is a buffer solution. It is an indirect acidic buffer solution, as the reaction constitutes a weak acid and Zinc sulfite salt formed from a weak acid and a strong base.

Is H2SO3 + Zn(OH)2 a complete reaction?

H2SO3 + Zn(OH)2 is not a complete reaction as H2SO3, a weak acid, remains in the solution due to its poor dissociation.

Is H2SO3 + Zn(OH)2 an exothermic or endothermic reaction?

H2SO3 + Zn(OH)2 is an exothermic reaction, as the reaction enthalpy is negative.

Is H2SO3 + Zn(OH)2 a redox reaction?

The reaction between H2SO3 and Zn(OH)2 is not a redox reaction, as neither oxidation nor reduction of any element takes place simultaneously.

Is H2SO3 + ZN(OH)2 a precipitation reaction ?

H2SO3 + Zn(OH)2 is a precipitation reaction as the product formed is a white precipitate of Zinc sulphite, which is insoluble in water.

Is H2SO3 + Zn(OH)2 reversible or irreversible reaction?

H2SO3 + Zn(OH)2 is an irreversible reaction because of the formation of Zinc sulphite precipitate, which is insoluble in water.

Is H2SO3 + Zn(OH)2 displacement reaction?

The reaction between H2SO3 + Zn(OH)2 is an example of a double displacement reaction because the anions and cations switch places to form salt and water. The reaction is given as,
H2SO3 + Zn(OH)2 = ZnSO3 + 2H2O

Conclusion

The sulfurous acid is used in the manufacture of inorganic salts, petroleum refining and metallurgical processes, dyes and fertilizers. The conjugate bases of the acid is HSO3–. Zinc hydroxide is basically an amphoteric oxide, that is, it is not actually an acid or a base individually but behaves as both an acid and base.