When calcium nitrate reacts with ammonium sulphate in solution, a double displacement reaction occurs, leading to the formation of calcium sulfate (CaSO₄), which precipitates out as a solid, and ammonium nitrate (NH₄NO₃), which remains in solution.
Understanding the Chemical Reaction
The interaction between calcium nitrate and ammonium sulphate is a classic example of a precipitation reaction, a type of double displacement reaction. In such reactions, the ions of two compounds exchange places to form two new compounds, one of which is often insoluble and forms a precipitate.
The Reactants
- Calcium Nitrate (Ca(NO₃)₂): An ionic compound highly soluble in water, often used as a fertilizer or in wastewater treatment. It dissociates into Ca²⁺ and NO₃⁻ ions in solution.
- Ammonium Sulphate ((NH₄)₂SO₄): Another highly soluble ionic compound, widely used as a fertilizer. It dissociates into NH₄⁺ and SO₄²⁻ ions in solution.
The Products Formed
When these two solutions are mixed, the following products are formed:
- Calcium Sulfate (CaSO₄): This is the key product of interest. According to the reference, CaSO₄ will precipitate out of the solution as a solid. Calcium sulfate is sparingly soluble in water, meaning most of it will fall out of solution as a solid white precipitate. It is commonly known as gypsum (dihydrate form) or anhydrite (anhydrous form).
- Ammonium Nitrate (NH₄NO₃): This compound remains dissolved in the solution as it is highly soluble in water. Ammonium nitrate is also a significant component of fertilizers.
The Role of Spectator Ions
In any chemical reaction occurring in a solution, some ions do not actively participate in the formation of new compounds. These are known as spectator ions. They remain in their ionic form throughout the reaction.
- In this reaction, the spectator ions are NO₃⁻ (from calcium nitrate) and NH₄⁺ (from ammonium sulfate). They are present on both sides of the full ionic equation and do not contribute to the formation of the precipitate.
Chemical Equations
To fully illustrate the reaction, we can write different types of chemical equations:
-
Molecular Equation:
Ca(NO₃)₂(aq) + (NH₄)₂SO₄(aq) → CaSO₄(s) + 2NH₄NO₃(aq)
(This equation shows the complete neutral compounds and their physical states: (aq) for aqueous/dissolved, (s) for solid/precipitate.) -
Complete Ionic Equation:
Ca²⁺(aq) + 2NO₃⁻(aq) + 2NH₄⁺(aq) + SO₄²⁻(aq) → CaSO₄(s) + 2NH₄⁺(aq) + 2NO₃⁻(aq)
(This equation breaks down all soluble ionic compounds into their constituent ions.) -
Net Ionic Equation:
Ca²⁺(aq) + SO₄²⁻(aq) → CaSO₄(s)
(By removing the spectator ions (NH₄⁺ and NO₃⁻) from the complete ionic equation, we get the net ionic equation, which only shows the species directly involved in forming the precipitate.)
Summary of the Reaction
| Aspect | Description |
|---|---|
| Reaction Type | Double Displacement (Precipitation Reaction) |
| Reactants | Calcium Nitrate (Ca(NO₃)₂), Ammonium Sulphate ((NH₄)₂SO₄) |
| Primary Product | Calcium Sulfate (CaSO₄) - precipitates out as a solid |
| Secondary Product | Ammonium Nitrate (NH₄NO₃) - remains dissolved in solution |
| Spectator Ions | Nitrate ions (NO₃⁻) and Ammonium ions (NH₄⁺) |
| Visible Result | Formation of a white solid (precipitate) in the solution |
Practical Insights
This reaction has several practical implications:
- Water Treatment: The precipitation of calcium sulfate can be relevant in industrial processes or natural waters where calcium ions need to be removed.
- Fertilizer Compatibility: When mixing fertilizers, understanding such reactions is crucial. While both calcium nitrate and ammonium sulfate are used as fertilizers, their direct mixture in concentrated solution might lead to the formation of insoluble calcium sulfate, reducing nutrient availability to plants if not handled correctly.
- Chemical Analysis: Precipitation reactions are fundamental in qualitative and quantitative chemical analysis for identifying ions or determining their concentrations.
In conclusion, mixing calcium nitrate and ammonium sulphate solutions results in the formation of insoluble calcium sulfate, which precipitates, and soluble ammonium nitrate, with nitrate and ammonium ions acting as spectators.
