Potassium(K), an alkali metal, is highly reactive, and H2SO3 (sulphurous acid) is a weak inorganic acid. Let us examine their reaction in detail.
K is a soft, silvery-white metal, solid at room temperature, and is an excellent conductor of electricity. Its reaction with water is violent and highly exothermic. H2SO3 is a colorless and corrosive acid, with a pungent-burning sulphur smell. K is a good reducing agent, as seen in its reaction with H2SO3.
In this article, let us discuss the reaction of H2SO3 + K, the type of reaction, the forces involved, buffer solution, and other related facts.
What is the product of H2SO3 and K?
Potassium sulphite and hydrogen gas are the products formed when H2SO3 reacts with K.
H2SO3 + 2K ———> K2SO3 + H2 ↑
What type of reaction is H2SO3 + K?
H2SO3 + K is a single displacement reaction.
How to balance H2SO3 + K?
The equation H2SO3 + K is balanced by the following steps.
H2SO3 + 2K = K2SO3 + H2
- Identify and count the number of moles of each element involved in both the sides of the reaction.
| Element | Reactant side | Product side |
|---|---|---|
| S | 1 | 2 |
| K | 1 | 1 |
| O | 3 | 3 |
| H | 2 | 2 |
- We find that the number of moles of all elements in the reactant and product side are equal except potassium (K).
- A coefficient of 2 is added before K in the reactant side so that the number of moles of K are same on both sides of the equation.
- The overall balanced equation is given by –
- H2SO3 + 2K = K2SO3 + H2
H2SO3 + K titration
H2SO3 + K will not undergo titration as K being a metal, will not be used in the titration.
H2SO3 + K net ionic equation
The net ionic equation between H2SO3 + K is:
H2SO3 (aq)+ K (s) = 2K+ (aq) + SO32- (aq) + H2 (g)
The following are the steps to derive the net ionic equation:
- Write the balanced molecular equation along with its physical state.
- H2SO3 (aq) + K (s) = K2SO3 (aq) + H2 (g)
- The electrolytes, which are strong, are split into their respective ions. H2SO3 is a weak electrolyte, K is a solid and H2 is a gas, so will not split. The equation now becomes,
- H2SO3 (aq)+ K (s) = 2K+ (aq) + SO32- (aq) + H2 (g)
- The charge in the above equation is also conserved. Therefore, the net ionic equation is –
- H2SO3 (aq)+ K (s) = 2K+ (aq) + SO32- (aq) + H2 (g)
H2SO3 + K conjugate pairs
- Conjugate base of H2SO3 as HSO3–
- K is a metal, so there is no conjugate pair for K.
H2SO3 + K intermolecular forces
- In H2SO3, Electrostatic forces, London dispersion forces, Van der Waals forces, and dipole-dipole interactions are the intermolecular forces that hold the hydrogen and sulphite ions together.
- Metallic bonding is seen in K, as it is a metal.
H2SO3 + K reaction enthalpy
H2SO3 + K reaction enthalpy is -467.87 KJ/mol. The enthalpy of the reaction is calculated using the values listed below,
| Reactants and Products | Enthalpy in KJ/mol |
|---|---|
| K(s) | 0.0 |
| H2SO3(aq) | -655.5 |
| K2SO3(aq) | -1123.37 |
| H2(g) | 0.0 |
- The enthalpy of formation of elements or molecules existing in their original state is taken as zero.
- ∆Hf°(reaction) = ∆Hf°(products) – ∆Hf°(reactants)
= -1123.37 – (-655.5)
= -467. 87 KJ/mol
Is H2SO3 + K a buffer solution?
H2SO3 + K will not form a buffer solution due to the presence of a metal (K) and weak sulphurous acid.
Is H2SO3 + K a complete reaction?
H2SO3 + K is a complete reaction since one of the products formed is hydrogen gas that gets evolved during the reaction.
Is H2SO3 + K an exothermic reaction?
H2SO3 + K is an exothermic reaction, as the reaction enthalpy is found to be negative.
Is H2SO3 + K a redox reaction?
H2SO3 + K is a redox reaction where,
- Potassium is oxidized from 0 to +1 oxidation state.
- Hydrogen is reduced from +1 to 0 oxidation state.
Is H2SO3 + K a precipitation reaction?
H2SO3 + K is not a precipitation reaction as the product formed is completely soluble in water, and no precipitate is observed.
Is H2SO3 + K an irreversible reaction?
H2SO3 + K is an irreversible reaction as the forward reaction is more favorable due to increased entropy associated with the liberation of gaseous hydrogen.
Is H2SO3 + K a displacement reaction?
H2SO3 + K is an example of a single displacement reaction, as potassium is more reactive than hydrogen and will displace it from its salt solution to form potassium sulphite.
Conclusion
The reaction of K with H2SO3 is less violent than with H2SO4, as sulphurous acid is a weak acid. The reaction proceeds with a violet-colored flame. Potassium is a very vital nutrient for human and plant growth.
Read more about following H2SO3 facts
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