Ammonia gas is highly soluble in water, but its solubility varies significantly with temperature. At colder temperatures, more ammonia can dissolve in water than at warmer temperatures.
Ammonia Solubility by Temperature
The solubility of ammonia in water is a key property that highlights its strong affinity for water molecules, primarily due to hydrogen bonding.
Here's a breakdown of its solubility at different temperatures:
| Temperature | Solubility (grams per 100 mL water) | Volume (Liters of gas per 1 Liter of water) |
|---|---|---|
| 0 °C | Approximately 90 g | Not specified for 0 °C |
| 25 °C | Approximately 32 g | Approximately 460 L (at room temperature) |
This means that at room temperature (around 25 °C), about 32 grams of ammonia gas can dissolve in 100 milliliters of water. To put this into perspective, at this temperature, a remarkable volume of roughly 460 liters of ammonia gas can dissolve in just 1 liter of water. This high solubility makes ammonia an excellent solvent for various chemical processes.
Understanding Ammonia in Water
When ammonia gas (NH₃) dissolves in water (H₂O), it undergoes a reversible reaction, forming ammonium ions (NH₄⁺) and hydroxide ions (OH⁻):
NH₃(g) + H₂O(l) ⇌ NH₄⁺(aq) + OH⁻(aq)
This equilibrium means that while some ammonia molecules react with water to form ions, many simply remain dissolved as hydrated ammonia molecules. For this reason, the term "ammonium hydroxide" is often a point of discussion among chemists, as a distinct NH₄OH molecule does not exist in solution; rather, it's an aqueous solution of ammonia in equilibrium with its ions.
Practical Applications
The high solubility of ammonia in water is crucial for many industrial and everyday applications:
- Cleaning Products: Ammonia water, often called "ammonia," is a common household cleaner due to its ability to dissolve grease and grime.
- Fertilizers: Aqueous ammonia solutions are used directly as fertilizers or as intermediates in the production of other nitrogen-based fertilizers.
- Industrial Processes: It's used in the production of various chemicals, including nitric acid, urea, and synthetic fibers.
- Refrigeration: While anhydrous ammonia is preferred for its high latent heat of vaporization, its solubility allows it to be used in absorption refrigeration systems.
Understanding the solubility of ammonia is vital for safe handling, storage, and utilization of this important chemical in various fields.
