Ferric hydroxide [Fe(OH)3] is a transition metal base and it reacts with sulfurous acid. Let us discuss the products obtained from the reaction between Fe(OH)3 and H2SO3.
H2SO3 and Fe(OH)3 react with each other and form ferric sulfite [Fe2(SO3)3] and water. Fe(OH)3 is a weak base and H2SO3 is also a weak acid. They undergo a neutralization reaction to form salt and water.
This article focuses on the products, enthalpy change, type, balancing method, conjugate pairs, intermolecular forces, and some more relevant topics of the reaction.
What is the product of H2SO3 and Fe(OH)3?
Ferric hydroxide, Fe(OH)3 reacts with the weak acid, H2SO3, and produces ferric sulfite [Fe2(SO3)3] and water (H2O).
2Fe(OH)3 (aq) + 3H2SO3 (aq) = Fe2(SO3)3 (aq) + 6H2O (l)
What type of reaction is H2SO3 + Fe(OH)3?
The reaction between H2SO3 + Fe(OH)3 is one type of-
- Acid-base reaction or neutralization reaction.
- Double displacement reaction or Metathesis reaction
- Exothermic reaction
- Irreversible reaction
How to balance H2SO3 + Fe(OH)3?
The following steps should be followed to balance a chemical reaction-
- Write the unbalanced chemical equation first using a right arrow sign as it is not balanced yet. Fe(OH)3 (aq) + H2SO3 (aq) → Fe2(SO3)3 (aq) + H2O (l)
- The mole numbers of each of the reacting elements should be determined on the reactant and product side.
| Elements | Mole numbers on the reactant side | Mole numbers on the product side |
| Fe | 1 | 2 |
| S | 1 | 3 |
| O | 6 | 10 |
| H | 5 | 2 |
- To balance both sides (reactant and product) we have to multiply 2 with the mole number of Fe(OH)3, 3 with H2SO3 on the reactant side, and 6 with the mole number of H2O on the product side.
- Therefore, the balanced equation will be – 2Fe(OH)3 (aq) + 3H2SO3 (aq) = Fe2(SO3)3 (aq) + 6H2O (l)
H2SO3 + Fe(OH)3 Titration
The titration between H2SO3 + Fe(OH)3 is not possible because H2SO3 is a weak acid and Fe(OH)3 is a weak base. The titration between a weak acid and a weak base is not possible because the equivalence point cannot be detected with accuracy due to not getting any sharp change in the titration curve.
H2SO3 + Fe(OH)3 Net Ionic Equation
The net ionic equation of the chemical reaction H2SO3 + Fe(OH)3 is–
2Fe3+ (aq) + 3OH– (aq) + 6H+ + 3SO32- (aq) = 2Fe3+(aq) + 3SO32- (aq) + 6H2O (l)
H2SO3 + Fe(OH)3 Conjugate Pairs
The conjugate pairs (pair of compounds differ by one proton) equation of H2SO3 + Fe(OH)3 is-
- The conjugate pair of H2SO3 is HSO3–
- The conjugate pair of H2O is OH–
H2SO3 + Fe(OH)3 Intermolecular Forces
The intermolecular forces act on H2SO3 + Fe(OH)3 are-
- The electrostatic force of attraction is working in Fe(OH)3. In the lattice of ferric hydroxide, the ferric ion (Fe3+), and hydroxyl ion (OH–) are attracted by each other by this strong interionic Columbic force.
- Being a covalent compound, dipole-dipole interaction and London dispersion forces are present in H2SO3. It can also form a very strong intermolecular hydrogen bonding with water molecules as well as itself.
- One of the products, ferric sulfite is ionic, and water is a covalent molecule. Therefore, the above intermolecular forces are also present between them.
H2SO3 + Fe(OH)3 Reaction Enthalpy
The enthalpy of the reaction H2SO3 + Fe(OH)3 are written below-
| Chemical compound | Formation enthalpy |
| H2SO3 | -552 KJ/mol (????H gas) -600.45 KJ/mol ( ????H liquid) |
| Fe(OH)3 | -824 KJ/mol |
| H2O | -286 KJ/mol |
Is H2SO3 + Fe(OH)3 a buffer solution?
H2SO3 + Fe(OH)3 is not a buffer solution because it is not a mixture of either a weak acid and its conjugate base (CH3COOH and CH3COONa, acidic buffer) or a weak base and its conjugate acid (NH4OH and NH4Cl, basic buffer). In this mixture, H2SO3 is a weak acid, and Fe(OH)3 acts as a weak base.
Is H2SO3 + Fe(OH)3 a complete reaction?
Only H2SO3 + Fe(OH)3 cannot be a complete reaction because it is only the reactants written here. If the actual products which are water and ferric sulfite are also written along with the reactants then it will be considered a complete reaction. Therefore, the complete reaction is written below-
2Fe(OH)3 (aq) + 3H2SO3 (aq) = Fe2(SO3)3 (aq) + 6H2O (l)
Is H2SO3 + Fe(OH)3 an exothermic or endothermic reaction?
H2SO3 + Fe(OH)3 is considered to be an exothermic reaction because the enthalpy of the neutralization is always exothermic. The energy released due to the formation of water molecules is greater than the energy absorbed for the progress of the reaction.
Is H2SO3 + Fe(OH)3 a redox reaction?
H2SO3 + Fe(OH)3 is not a redox reaction because in this reaction no electron transfer is taking place. Therefore, there is no change in the oxidation state of Fe, H, O, and S. All the elements maintain their oxidation state throughout the reaction.
| Elements | Oxidation state on the reactant side | Oxidation state on the product side |
| Fe | +3 | +3 |
| H | +1 | +1 |
| S | +4 | +4 |
| O | -2 | -2 |
Is H2SO3 + Fe(OH)3 a precipitation reaction?
H2SO3 + Fe(OH)3 is not a precipitation reaction because none of the two products (ferric sulfite and water) are obtained as a precipitate after the completion of the reaction. The product, ferrous sulfite [Fe2(SO3)3] is completely soluble in water. It is rather a displacement reaction.
Is H2SO3 + Fe(OH)3 a reversible or irreversible reaction?
H2SO3 + Fe(OH)3 is an irreversible reaction because the product side is more stable than the reactant side. Besides that, it is a neutralization reaction, and all the neutralization reaction becomes irreversible due to the formation of more stable salt and water.
Is H2SO3 + Fe(OH)3 displacement reaction?
H2SO3 + Fe(OH)3 is a double-displacement reaction because each of the reacting chemicals is displaced by each other to form the products. In this reaction, Fe is displaced by hydrogen from ferric hydroxide whereas hydrogen is displaced by Fe from sulfurous acid.
Conclusion
Ferric hydroxide acts as an iron supplement in the living body and helps to cure iron deficiency anemia. Sulfurous acid also has different uses in the manufacture of fertilizers, dyes detergents, inorganic salts, etc.
Read more about following H2SO3 facts
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