Yes, calcium oxide (CaO), also known as quicklime, can cause hardness in water.
When calcium oxide is added to water, it reacts to form calcium hydroxide (Ca(OH)₂), also known as slaked lime. This calcium hydroxide then dissolves in the water, increasing the concentration of calcium ions (Ca²⁺).
Calcium ions are a primary contributor to water hardness. Hard water is generally defined as water that contains a high concentration of multivalent cations, primarily calcium (Ca²⁺) and magnesium (Mg²⁺) ions. These ions react with soap, preventing it from lathering properly, and can form scale in pipes, water heaters, and other appliances.
Here's a breakdown:
- Reaction: CaO (Calcium Oxide) + H₂O (Water) → Ca(OH)₂ (Calcium Hydroxide)
- Dissolution: Ca(OH)₂ (Calcium Hydroxide) ⇌ Ca²⁺ (Calcium Ions) + 2OH⁻ (Hydroxide Ions)
- Increased Hardness: The presence of Ca²⁺ ions increases the hardness of the water.
Therefore, adding calcium oxide to water ultimately results in an increase in calcium ions, contributing to water hardness.
