Calcium hydroxide (Ca(OH)2)

Definition

Calcium hydroxide, commonly known as slaked lime, is an inorganic compound formed from the reaction of calcium oxide with water. It acts as a strong base in aqueous solutions and is important in various chemical processes, particularly in the context of acid-base reactions, where it can neutralize acids and influence pH levels.

5 Must Know Facts For Your Next Test

1. Calcium hydroxide has a solubility of about 1.73 g per liter in water, which means it is not highly soluble but still significantly affects the pH of solutions when dissolved.
2. It can be used in various applications, including water treatment, food processing, and as a building material in mortar and plaster.
3. When calcium hydroxide reacts with carbon dioxide in the air, it forms calcium carbonate, which is a process called carbonation.
4. Calcium hydroxide's ability to accept protons makes it a strong base with a high Kb value, indicating its effectiveness in neutralizing acids.
5. In the context of acid-base strength, calcium hydroxide can be used to demonstrate the principles of strong bases due to its complete dissociation in water.

Review Questions

• How does calcium hydroxide behave when dissolved in water, and what implications does this have for its use in neutralizing acids?
  • When calcium hydroxide dissolves in water, it dissociates completely into calcium ions (Ca^2+) and hydroxide ions (OH^-), creating a strongly basic solution. This behavior means that calcium hydroxide can effectively neutralize acids by providing hydroxide ions that react with hydrogen ions (H+) from the acid. The resulting neutralization reaction produces water and a salt, allowing for control over the acidity of various solutions.
• Discuss the role of calcium hydroxide in environmental applications such as water treatment and its effects on pH levels.
  • In environmental applications like water treatment, calcium hydroxide is used to raise pH levels in acidic waters. When added to water, it increases alkalinity by providing hydroxide ions, which can neutralize acidic contaminants. This process not only improves water quality but also facilitates the precipitation of heavy metals and other pollutants, making it an essential agent for maintaining ecological balance in aquatic systems.
• Evaluate the significance of calcium hydroxide's Kb value in determining its strength as a base compared to other common bases.
  • The Kb value of calcium hydroxide reflects its strong basic nature due to its complete dissociation into Ca^2+ and OH^- ions in solution. When comparing it to other common bases like sodium hydroxide or potassium hydroxide, which also exhibit high Kb values, calcium hydroxide demonstrates similar effectiveness in neutralizing acids. However, its lower solubility limits its application in situations where highly concentrated bases are required. Understanding its Kb value helps predict how well it will perform in various acid-base reactions, providing insights into its practical uses across different industries.

Related terms

pH:

A measure of the acidity or basicity of a solution, calculated as the negative logarithm of the hydrogen ion concentration.

Neutralization:

A chemical reaction between an acid and a base that produces water and a salt, resulting in a solution with a pH closer to 7.

Hydroxide Ion (OH-): A negatively charged ion formed when a base dissolves in water, contributing to the basicity of the solution.