Temporary hardness in water is caused by the presence of specific dissolved minerals. According to provided information, bicarbonates and carbonates of calcium and magnesium are responsible for this type of water hardness. This hardness is termed "temporary" because it can be removed through a simple process like boiling.
Understanding Temporary Hardness
Temporary hardness refers to the type of water hardness that can be eliminated by boiling the water. The reason boiling works is due to the chemical properties of the dissolved minerals.
Cause of Temporary Hardness
The primary cause of temporary hardness is the presence of:
- Calcium bicarbonate (Ca(HCO3)2)
- Magnesium bicarbonate (Mg(HCO3)2)
- Calcium carbonate (CaCO3)
- Magnesium carbonate (MgCO3)
These compounds dissolve in water and contribute to its hardness. When the water is heated, these bicarbonates decompose, forming carbonates which are insoluble and precipitate out of the water, thus reducing the hardness.
Removing Temporary Hardness
Boiling is an effective method for removing temporary hardness because it promotes the decomposition of bicarbonates:
Ca(HCO₃)₂ (aq) → CaCO₃ (s) + H₂O (l) + CO₂ (g)
Mg(HCO₃)₂ (aq) → MgCO₃ (s) + H₂O (l) + CO₂ (g)The carbonates (CaCO3 and MgCO3) are insoluble and form a solid precipitate (scale) at the bottom or sides of the container. This process effectively removes the calcium and magnesium ions from the water, making it softer. The carbon dioxide is released as gas.
Table Summarizing Temporary Hardness
| Feature | Description |
|---|---|
| Cause | Bicarbonates and carbonates of calcium and magnesium. |
| Primary Compounds | Calcium bicarbonate (Ca(HCO3)2), Magnesium bicarbonate (Mg(HCO3)2) |
| Removal Method | Boiling |
| Boiling Process | Bicarbonates decompose into insoluble carbonates, water, and carbon dioxide. |
