Neutralisation of aqueous ammonia by dilute sulphuric acid is a chemical reaction where an acid (sulphuric acid) reacts with a base (ammonia) to form a salt (ammonium sulphate) and water.
The Chemical Reaction
This process is a classic acid-base neutralisation. Ammonia ($\text{NH}_3$) acts as a base, reacting with the acid ($\text{H}_2\text{SO}_4$). When ammonia is in aqueous solution ($\text{NH}_3\text{(aq)}$), it forms ammonium ions ($\text{NH}_4^+$) and hydroxide ions ($\text{OH}^-$) to some extent, but the overall reaction is represented by the formation of the ammonium ion from ammonia reacting with the acid. The provided reference states that Ammonia is directly neutralized with sulphuric acid to produce ammonium sulphate.
The balanced chemical equation representing this neutralisation is:
$2\text{NH}_3\text{(aq)} + \text{H}_2\text{SO}_4\text{(aq)} \rightarrow (\text{NH}_4)_2\text{SO}_4\text{(aq)}$
This reaction shows two molecules of ammonia reacting with one molecule of sulphuric acid to yield one molecule of ammonium sulphate.
Reaction Summary
| Reactants | Products | Type of Reaction |
|---|---|---|
| Aqueous Ammonia | Ammonium Sulphate | Neutralisation |
| Sulphuric Acid | Water |
(Note: While water is formed in a typical strong acid-strong base neutralisation forming a soluble salt, in this reaction with aqueous ammonia and sulphuric acid forming solid/dissolved ammonium sulphate, the product primarily highlighted is the salt, with water being the solvent.)
Practical Application and Heat Utilisation
The neutralisation reaction between ammonia and sulphuric acid is exothermic, meaning it releases heat. As highlighted in the reference, this heat can be strategically used in industrial processes:
- Interconnected Equipment: The neutralizer evaporator and the crystallizer are interconnected.
- Heat Recovery: The heat released during neutralization is utilized to evaporate water in the ammonium sulphate slurry.
This integration makes the production of ammonium sulphate more energy-efficient, as the heat generated by the reaction helps to concentrate the product solution and facilitate crystallisation, which is often the next step in obtaining solid ammonium sulphate.
Key Points
- Reactants: Aqueous ammonia ($\text{NH}_3$) and dilute sulphuric acid ($\text{H}_2\text{SO}_4$).
- Product: Ammonium sulphate ($(\text{NH}_4)_2\text{SO}_4$).
- Process Type: Acid-base neutralisation.
- Energy: The reaction is exothermic, releasing heat.
- Industrial Use: The released heat can be used for evaporation and crystallisation of the product, as stated in the reference.
This process is significant in the production of ammonium sulphate, a widely used fertiliser.
