Why is Water a Solvent? (And Why not Solution?) (+Examples)

Water is a solvent (also known as the “universal solvent”) because it has the ability to dissolve a wide range of substances. In most cases, when substances dissolve in water, water acts as the solvent. ¹

Well, this was just a simple answer. But there are few more things to know about this topic which will make your concept super clear.

So let’s dive right into it.

Why is water a solvent?

Water is considered a universal solvent because of its unique molecular structure and chemical properties. Water is a polar molecule, meaning it has a partial negative charge on one end and a partial positive charge on the other end. This polarity allows water to interact with and dissolve many different types of solutes. ²

When a solute, such as salt or sugar, is added to water, the polar water molecules surround and separate the individual ions or molecules of the solute.

This happens because the partial positive charge of the water molecule is attracted to the negative ion of the solute, and the partial negative charge of the water molecule is attracted to the positive ion of the solute.

These interactions break apart the solute and allow it to dissolve in the water.

Additionally, water is capable of forming hydrogen bonds, which are strong attractions between the positively charged hydrogen atoms of one water molecule and the negatively charged oxygen atoms of another water molecule. ^{3 4}

This property allows water to dissolve many polar solutes, such as alcohols, acids, and some organic compounds.

Overall, the polar nature and ability to form hydrogen bonds make water an excellent solvent for a wide range of substances, making it an essential component of many natural and industrial processes.

Examples of water as a solvent

Water is commonly used as a solvent for various substances. Here are a few examples:

1. Salt Dissolving in Water: When table salt (sodium chloride) is added to water, the water molecules surround the sodium and chloride ions, effectively separating them and dissolving the salt. ⁵
2. Sugar Dissolving in Water: Sugar (such as table sugar or sucrose) readily dissolves in water. The polar water molecules interact with the polar hydroxyl groups in sugar, causing the sugar molecules to separate and dissolve in the water. ⁶
3. Acids Dissolving in Water: Many acids, such as hydrochloric acid (HCl) or sulfuric acid (H2SO4), dissolve in water to form aqueous solutions. ⁷ The water molecules surround the individual ions of the acid, breaking them apart and allowing them to mix uniformly in the water.
4. Alcohols Dissolving in Water: Many alcohols, like ethanol (the type of alcohol found in alcoholic beverages), dissolve in water due to the polarity of both water and alcohol molecules. ⁸ This property allows for the creation of various alcoholic beverages and the use of water as a solvent in the production of tinctures and extracts.
5. Dyes Dissolving in Water: Water is often used as a solvent for dyes and pigments. The water molecules interact with the dye molecules, enabling them to separate and dissolve, leading to the creation of colored solutions.
6. Gases Dissolving in Water: Water is also capable of dissolving certain gases, such as oxygen and carbon dioxide. This ability is crucial for the exchange of gases in biological systems, like the oxygen dissolving in blood or the absorption of carbon dioxide by water in aquatic environments. ⁹

These examples demonstrate the versatility of water as a solvent and highlight its importance in various fields, including chemistry, biology, and industry.

Why is water not a solution?

Water is not considered a solution because it does not have solutes dissolved in it. A solution is a homogeneous mixture of two or more substances, with one substance (the solute) dissolved in another (the solvent). ¹⁰

In more detail, water itself can act as a solvent and form solutions when other substances dissolve in it. However, when we refer to water alone, it is not considered a solution. 

Water is classified as a pure substance and is often referred to as a “solvent” because of its ability to dissolve a wide range of solutes. In a solution, the solute particles become uniformly dispersed in the solvent particles, creating a homogeneous mixture. 

While water can dissolve various solutes, when it is in its pure form, it does not contain dissolved substances, and therefore, it is not classified as a solution.

Further reading

Is Air a Compound or Mixture?
Why is Water a Compound?
Is Water an Element?
Is Air an Element?
Why is Air a Homogeneous Mixture?

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