Write chemical, complete ionic and net ionic equations for the following reactions that produce water a) Sulfuric acid and aqueous potassium hydroxide b) Hydrosulfuric acid and aqueous calcium hydroxide c) Phosphoric acid and aqeuous magnesium hydroxide
Write chemical, complete ionic and net ionic equations for the following reactions that produce water
a) Sulfuric acid and aqueous potassium hydroxide
b) Hydrosulfuric acid and aqueous calcium hydroxide
c) Phosphoric acid and aqeuous magnesium hydroxide
The Correct Answer and Explanation is:
Here are the chemical, complete ionic, and net ionic equations for each of the acid-base reactions that result in the formation of water:
a) Sulfuric acid (H₂SO₄) and aqueous potassium hydroxide (KOH)
Chemical Equation:
H₂SO₄(aq) + 2KOH(aq) → K₂SO₄(aq) + 2H₂O(l)
Complete Ionic Equation:
H⁺(aq) + HSO₄⁻(aq) + 2K⁺(aq) + 2OH⁻(aq) → 2K⁺(aq) + SO₄²⁻(aq) + 2H₂O(l)
Net Ionic Equation:
2OH⁻(aq) + 2H⁺(aq) → 2H₂O(l)
→ simplified: H⁺(aq) + OH⁻(aq) → H₂O(l) (but retain coefficients to match actual stoichiometry)
b) Hydrosulfuric acid (H₂S) and aqueous calcium hydroxide (Ca(OH)₂)
Chemical Equation:
H₂S(aq) + Ca(OH)₂(aq) → CaS(aq) + 2H₂O(l)
Complete Ionic Equation:
H₂S(aq) + Ca²⁺(aq) + 2OH⁻(aq) → Ca²⁺(aq) + S²⁻(aq) + 2H₂O(l)
Net Ionic Equation:
H₂S(aq) + 2OH⁻(aq) → S²⁻(aq) + 2H₂O(l)
c) Phosphoric acid (H₃PO₄) and aqueous magnesium hydroxide (Mg(OH)₂)
Chemical Equation:
2H₃PO₄(aq) + 3Mg(OH)₂(aq) → Mg₃(PO₄)₂(s) + 6H₂O(l)
Complete Ionic Equation:
6H⁺(aq) + 2PO₄³⁻(aq) + 3Mg²⁺(aq) + 6OH⁻(aq) → Mg₃(PO₄)₂(s) + 6H₂O(l)
Net Ionic Equation:
6H⁺(aq) + 6OH⁻(aq) → 6H₂O(l)
Explanation
These reactions are classic examples of acid-base neutralization, where an acid reacts with a base to form water and a salt. The chemical equation shows the substances involved and the overall transformation. The complete ionic equation breaks down all strong electrolytes into ions, revealing the actual species present in solution. The net ionic equation eliminates spectator ions and shows only the ions that participate in the reaction.
In reaction (a), sulfuric acid (a strong diprotic acid) donates two protons (H⁺) to react with hydroxide ions (OH⁻) from potassium hydroxide, forming water. The salt formed is potassium sulfate (K₂SO₄), a soluble compound. Both H₂SO₄ and KOH dissociate fully in water.
For (b), hydrosulfuric acid (H₂S) is a weak diprotic acid. It reacts with the strong base calcium hydroxide. The base provides OH⁻ ions that react with H⁺ from H₂S to form water. The leftover anion (S²⁻) forms a salt (CaS) with the Ca²⁺ ions. This is slightly more complex because H₂S does not fully dissociate in solution.
In (c), phosphoric acid is a triprotic weak acid, and magnesium hydroxide is a weak base. Despite the weak dissociation of both in water, when they react, they neutralize to form solid magnesium phosphate (an insoluble salt) and water. Because Mg₃(PO₄)₂ is insoluble, it precipitates out, which is why it appears in the chemical equation as a solid.
Each net ionic equation highlights the essence of neutralization: the combination of H⁺ and OH⁻ to form water, sometimes accompanied by the formation of a precipitate depending on solubility.
