Salts are formed through a chemical process known as neutralisation.
What is Neutralisation?
According to the provided information, a neutralization reaction is when an acid and a base react to form water and a salt. This fundamental reaction is a cornerstone of chemistry, particularly in acid-base chemistry.
The Neutralisation Process
The essence of neutralisation lies in the reaction between the acidic and basic components. Acids typically release hydrogen ions (H⁺) in solution, while bases release hydroxide ions (OH⁻) or accept H⁺ ions.
The reference states that neutralisation involves the combination of H+ ions and OH- ions to generate water. This is the core ionic reaction:
H⁺(aq) + OH⁻(aq) → H₂O(l)
While the H⁺ and OH⁻ ions combine to form water, the remaining ions from the acid and base pair up to form a salt.
Let's consider a general example:
- An acid (like hydrochloric acid, HCl) consists of H⁺ and an anion (like Cl⁻).
- A base (like sodium hydroxide, NaOH) consists of a cation (like Na⁺) and OH⁻.
When these react:
HCl(aq) + NaOH(aq) → H₂O(l) + NaCl(aq)
In this reaction:
- The H⁺ from HCl combines with the OH⁻ from NaOH to form water (H₂O).
- The remaining cation (Na⁺ from NaOH) combines with the remaining anion (Cl⁻ from HCl) to form the salt, sodium chloride (NaCl).
Components of a Neutralisation Reaction
| Component | Source | Role |
|---|---|---|
| Acid | Provides H⁺ ions | Reacts with base |
| Base | Provides OH⁻ ions or accepts H⁺ ions | Reacts with acid |
| Water | Formed from H⁺ and OH⁻ combination | Product of reaction |
| Salt | Formed from the cation of the base and anion of the acid | Product of reaction |
pH After Neutralisation
The pH of the resulting solution after neutralisation depends on the strength of the acid and base used. The reference mentions, "The neutralization of a strong acid and strong base has a pH equal to 7." A pH of 7 is considered neutral on the pH scale, indicating that the solution is neither acidic nor basic. However, neutralisation reactions involving weak acids or bases can result in solutions that are slightly acidic or basic (pH not equal to 7).
Examples of Salt Formation by Neutralisation
Here are a few specific examples:
-
Formation of Sodium Chloride (Table Salt):
- Reactants: Hydrochloric Acid (HCl) [Strong Acid] + Sodium Hydroxide (NaOH) [Strong Base]
- Equation: HCl + NaOH → NaCl + H₂O
- Salt Formed: Sodium Chloride (NaCl)
-
Formation of Potassium Nitrate:
- Reactants: Nitric Acid (HNO₃) [Strong Acid] + Potassium Hydroxide (KOH) [Strong Base]
- Equation: HNO₃ + KOH → KNO₃ + H₂O
- Salt Formed: Potassium Nitrate (KNO₃)
-
Formation of Calcium Sulfate:
- Reactants: Sulfuric Acid (H₂SO₄) [Strong Acid] + Calcium Hydroxide (Ca(OH)₂) [Strong Base]
- Equation: H₂SO₄ + Ca(OH)₂ → CaSO₄ + 2H₂O
- Salt Formed: Calcium Sulfate (CaSO₄)
In summary, salts are formed through the reaction of an acid and a base, which produces water and a salt. This process involves the reaction of hydrogen ions from the acid and hydroxide ions from the base to form water, leaving the remaining ions to combine and form the salt.
