In simple terms, ‘Anhydrous’ means ‘without water’. The word is a compound word made up of “an” (which in this case means “without”), and “hydrous” (refers to “water”).
The word is often used to describe chemical products in dry or liquid form that do not contain water (i.e. “Sodium Sulfate Anhydrous”).
Yes, even liquids can be anhydrous! Just because a substance is present in liquid form does NOT mean that any part of that liquid is water (H2O).
Anhydrous products may be used for a wide variety of applications, depending on the functionality of the substance that is “without water”.
Do anhydrous products have a smell? That depends on the chemical or substance that IS anhydrous…
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In this article:
- Is Anhydrous a Good Thing?
- What are Anhydrous Products Used For?
- Examples of Anhydrous Products
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Is Anhydrous a Good Thing?
Whether or not a substance contains water doesn’t always indicate that it is either helpful or harmful; it just means that it isn’t a hydrated form of whatever it is.
It doesn’t necessarily mean that the product is ‘pure’, either. You can have a product that is made up of 2 or more constituents, and in the sense of ‘pure’, it ISN’T purely one or the other. A blend that is “without water” could be considered anhydrous, but not pure.
Are Anhydrous products ever hazardous? Whether or not a substance contains water can change the state of the product, and actually can affect the hazards the product represents to people or the environment. Of course, this depends on what the product is. One example of a product that takes on additional hazards (when it exists without water) is Ammonium Hydroxide. If the water is removed, it becomes Anhydrous Ammonia, which is a very hazardous gas.
What are Anhydrous Products Used For?
There are several reasons why anhydrous products may be used….
- Some products are more stable when they are completely dry.
- Anhydrous products may be more consumer-friendly.
- They may be more economical to ship (concentrated vs a heavy water solution).
- One form or the other may be better for a specific application. There are certain chemical reactions where the anhydrous form will either react better, react more efficiently, react possibly at a lower temperature, or react in a way that creates less potentially undesirable byproducts.
Wherever water may not be wanted for a number of reasons, anhydrous products can be used.
Examples of Anhydrous Products
(Note: Products such as table salt may be anhydrous when they are first made, but if they are hygroscopic in nature, they will absorb water from the atmosphere if left exposed to air.)
