What is the Difference Between Calcium Oxide and Calcium Hydroxide?

Calcium oxide and calcium hydroxide are both calcium compounds, but they have different properties and uses. The main differences between them include:

Density: Calcium oxide has a high density (65 lb/ft³), while calcium hydroxide has a lower density (35 lb/ft³).
Reactivity: Calcium oxide is more reactive than calcium hydroxide. Calcium hydroxide is already neutralized and will not undergo oxidation, making it suitable for mixing with water.
Chemical Formula: Calcium oxide has the chemical formula CaO, while calcium hydroxide has the chemical formula Ca(OH)².
Production: Calcium oxide is produced by heating limestone in a kiln, which causes the calcium carbonate to break down and release carbon dioxide, leaving behind calcium oxide. Calcium hydroxide is produced by mixing calcium oxide with water.
Applications: Calcium oxide, also known as quicklime, is used for various applications such as soil stabilization, water treatment, steel production, glass production, and cement production. Calcium hydroxide, also known as hydrated lime, is used in the manufacturing of some pesticides, paints, waterproofing materials, and as an additive to oils and lubricants. It is also used in the paper industry to treat wood for easier conversion to pulp.
Safety: Both calcium oxide and calcium hydroxide can cause chemical burns if they come into contact with unprotected skin. However, calcium hydroxide is generally considered less hazardous than calcium oxide.

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Comparative Table: Calcium Oxide vs Calcium Hydroxide

Here is a table comparing the differences between calcium oxide and calcium hydroxide:

Property	Calcium Oxide (CaO)	Calcium Hydroxide (Ca(OH)₂)
Chemical Formula	CaO	Ca(OH)₂
Name	Quicklime, Burnt Lime	Slaked Lime, Hydrated Lime
Formation	Thermal decomposition of limestone or seashells at high temperatures (above 625°C)	Formed by adding water to calcium oxide in a process called slaking
Appearance	White, crystalline solid	Colorless crystal or white powder
Solubility	Low solubility in water	Poorly soluble in water, with solubility increasing from 0.66 g/L at 100°C to 1.89 g/L at 0°C
Reactivity	Highly reactive, can resist melting even at very high temperatures (up to 2600°C)	Moderately reactive, used in certain industrial and construction applications
Uses	1. Main ingredient in cement production. 2. Flux in medium and high-temperature glazes. 3. Component in various ceramic and glass manufacturing processes.	1. Regulating pH in water treatment. 2. Stabilizing soil in roads and runways. 3. Manufacturing glass and ceramics.

Calcium oxide and calcium hydroxide are both inorganic compounds of calcium, but they have different chemical properties and uses. Calcium oxide is produced by heating calcium carbonate, while calcium hydroxide is formed by adding water to calcium oxide.

Guilherme Mazui

Guilherme Mazui is graduated in journalism from the Federal University of Minas Gerais (UFMG) and a master's degree in Communication from the University of São Paulo (USP). In addition, he has experience in advertising writing and has worked as a content editor in several companies.