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Calcium Chloride vs. Calcium Chloride Dihydrate: What's the Difference?

Edited by Aimie Carlson || By Harlon Moss || Published on December 17, 2023
Calcium chloride is an anhydrous salt, while calcium chloride dihydrate contains two water molecules bound within its crystal structure.

Key Differences

Calcium chloride (CaCl₂) and calcium chloride dihydrate (CaCl₂·2H₂O) are two forms of the same chemical compound, but they differ in their water content. Calcium chloride is an anhydrous substance, meaning it does not contain water molecules within its crystal structure. On the other hand, calcium chloride dihydrate contains two molecules of water for every molecule of calcium chloride. This difference in water content significantly influences their physical properties, such as density and melting point.
In terms of applications, both calcium chloride and calcium chloride dihydrate are used in various industrial and commercial settings, but their usage can be influenced by their physical properties. Calcium chloride, being anhydrous, is highly effective as a drying agent. It can absorb moisture from the environment, making it ideal for use in desiccants. Conversely, calcium chloride dihydrate, with its water content, is less potent as a desiccant but is often used in similar applications where a less aggressive moisture absorption is required.
Chemically, both calcium chloride and calcium chloride dihydrate have similar properties, as they are essentially the same compound. However, the presence of water in calcium chloride dihydrate can affect its chemical behavior in certain reactions. For instance, when used in reactions where water is a factor, such as in brine solutions for refrigeration systems, the dihydrate form might have different efficiency or reactivity compared to the anhydrous form.
In terms of solubility, both calcium chloride and calcium chloride dihydrate are highly soluble in water. However, the process of dissolution and the heat evolved can vary. Calcium chloride, being anhydrous, can generate a significant amount of heat when dissolved in water, a property utilized in various heating applications. In contrast, calcium chloride dihydrate, already containing water molecules, produces less heat upon dissolution, making it a safer option in applications where heat generation is a concern.

Comparison Chart

Chemical Formula


Hydration State

Contains two water molecules

Physical Form

White, crystalline solid
Similar, but different crystal structure

Moisture Absorption

Highly hygroscopic
More stable, but can dehydrate at high temperatures


De-icing, dust control, desiccant
De-icing, food processing, less aggressive desiccant

Calcium Chloride and Calcium Chloride Dihydrate Definitions

Calcium Chloride

Calcium chloride is a hygroscopic salt used for de-icing.
They spread calcium chloride on the roads to prevent ice formation.

Calcium Chloride Dihydrate

It is less hygroscopic compared to its anhydrous form.
Calcium chloride dihydrate is preferred for storage due to its stability.

Calcium Chloride

It's used in concrete to accelerate curing.
Adding calcium chloride to concrete mix reduces setting time.

Calcium Chloride Dihydrate

It's used as a source of calcium in food.
Calcium chloride dihydrate fortifies sports drinks with calcium.

Calcium Chloride

It's an anhydrous compound used as a desiccant.
Calcium chloride effectively absorbs moisture in packaging.

Calcium Chloride Dihydrate

Calcium chloride dihydrate is used in beer brewing for water treatment.
Brewers use calcium chloride dihydrate to adjust the mineral content of water.

Calcium Chloride

Calcium chloride serves as a firming agent in canned vegetables.
Calcium chloride keeps pickles crisp during the canning process.

Calcium Chloride Dihydrate

Calcium chloride dihydrate is a hydrated form of calcium chloride.
Calcium chloride dihydrate is used in laboratories for experiments.

Calcium Chloride

Calcium chloride is used in sports to maintain dry surfaces.
The tennis court was treated with calcium chloride to dry it quickly.

Calcium Chloride Dihydrate

It's used in medicinal formulations for electrolyte balance.
Intravenous solutions contain calcium chloride dihydrate for electrolyte replenishment.


What is calcium chloride dihydrate?

A hydrated form of calcium chloride with two water molecules.

Can calcium chloride absorb moisture?

Yes, it's highly hygroscopic.

Are both compounds used in food processing?

Yes, but calcium chloride dihydrate is more common in food.

Can calcium chloride dihydrate revert to calcium chloride?

Yes, upon heating or prolonged exposure to dry conditions.

What's the role of calcium chloride in beer brewing?

It adjusts water mineral content for flavor enhancement.

Is calcium chloride dihydrate less hygroscopic?

Yes, it's more stable and less prone to absorbing moisture.

What happens to calcium chloride dihydrate when heated?

It loses water and can convert to anhydrous calcium chloride.

Is calcium chloride safe for environmental use?

In controlled quantities, but it can be harmful in excess.

What is calcium chloride?

A hygroscopic salt used for de-icing and as a desiccant.

Is calcium chloride dihydrate used in medicines?

Yes, for electrolyte balance in intravenous solutions.

Are both forms of calcium chloride toxic?

In large quantities, yes, but they're generally safe in controlled applications.

Can calcium chloride be used in concrete?

Yes, it accelerates the curing process.

Can either form cause skin irritation?

Yes, especially the anhydrous form, due to its hygroscopic nature.

Can calcium chloride dihydrate be used in laboratories?

Yes, particularly in chemical experiments.

Is calcium chloride used in sports?

Yes, for drying wet surfaces.

Can calcium chloride be used for dust control?

Yes, it's effective in binding dust particles.

How does calcium chloride affect canned foods?

It acts as a firming agent to maintain texture.

Is calcium chloride dihydrate used in intravenous solutions?

Yes, for calcium supplementation.

What is the main advantage of calcium chloride dihydrate over the anhydrous form?

Its greater stability and less aggressive moisture absorption.

Does calcium chloride dihydrate have a special storage requirement?

It should be stored in a cool, dry place but is less sensitive than anhydrous calcium chloride.
About Author
Written by
Harlon Moss
Harlon is a seasoned quality moderator and accomplished content writer for Difference Wiki. An alumnus of the prestigious University of California, he earned his degree in Computer Science. Leveraging his academic background, Harlon brings a meticulous and informed perspective to his work, ensuring content accuracy and excellence.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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