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Short answer
An aqueous solution is a solution in which water is the solvent: the component present in the greater amount, with one or more solutes dissolved in it. “Aqueous” names the solvent, not the physical state. A solution that uses a different solvent, such as 2-propanol, is a non-aqueous solution, and not every substance dissolves in water to a useful extent.
What is meant by aqueous solution in chemistry?
OpenStax Chemistry 2e defines solutions as “homogeneous mixtures of two or more substances”. The solvent is the component present at a significantly greater concentration, and the solutes are those present in relatively lesser concentrations. When that solvent is water, the result is an aqueous solution.
Water is so common as a solvent that, in the same textbook’s words, “the word solution has come to imply an aqueous solution to many people.” That habit is why the qualifier is easy to drop in conversation and why it matters in a laboratory record, where the solvent has to be stated and cannot be assumed.
How solutes dissolve: solvent, solute and the solubility limit
Three ideas from the same OpenStax chapters cover most of what a lab worker needs to reason about an aqueous solution.
- Solubility is a maximum. The solubility of a solute in a particular solvent is the maximum concentration that may be achieved under given conditions.
- Saturated versus unsaturated. A solution whose concentration equals the solubility is saturated; one whose concentration is below the solubility is unsaturated.
- Like dissolves like. Polar solutes tend to dissolve in polar solvents and nonpolar solutes in nonpolar solvents. Water is the everyday polar solvent, so polar solutes are the natural fit for aqueous work.
Concentration is a separate question from solvent. The same aqueous solution can be described by mass percent, molarity or molality; see the CASRAI guides on mass percent solutions, molarity calculations and the molal formula.
What is a non-aqueous solution?
A non-aqueous solution is a solution whose solvent is something other than water. OpenStax notes that almost any gas, liquid or solid can act as a solvent, and its Table 11.1 gives examples across states of matter: nitrogen in air, copper as the solvent for zinc in brass, and 2-propanol as the solvent in rubbing alcohol.
Is liquid the same as aqueous?
No. “Liquid” describes a physical state; “aqueous” describes which solvent is used. Many aqueous solutions are liquids, but a liquid solution can have a non-water solvent, and solutions also exist as gases (air) and solids (brass). Treating the two words as synonyms is the most common mix-up.
| Question | Aqueous solution | Non-aqueous solution |
|---|---|---|
| Solvent | Water | Any solvent other than water, for example 2-propanol (OpenStax Table 11.1) |
| Which solutes it suits | Polar solutes, by “like dissolves like” | Nonpolar solutes favour nonpolar solvents |
| State of matter | Often a liquid, but not required to be | Not tied to a state: air and brass are solutions too |
Where it matters for labs and supply decisions
Solvent identity is part of what a prepared solution is, so a solution record should name it. A container marked only “1 M NaCl” does not say whether the solvent is water, and “aqueous” is only true if it is.
A short checklist for reading or writing a solution record
- Is the solvent named, and is it water?
- Is the stated concentration below the solute’s solubility in that solvent, so the solution is unsaturated, or at the limit, so it is saturated?
- Is the solute polar or nonpolar, and does it match the solvent?
- If two liquids are being combined, are they miscible (infinite mutual solubility) or immiscible (they do not mix to an appreciable extent)?
For the preparation side, including buffers, see the CASRAI buffer and solution preparation guide. For the question of which materials a given liquid can touch, see the chemical compatibility chart for wetted materials.
Common misunderstandings
Are all substances soluble in water?
No. Solubility is the extent to which a substance may be dissolved in water or any solvent, and it can be relatively large (soluble) or relatively low (insoluble). OpenStax Chemistry 2e, section 4.2, includes a table of insoluble ionic compounds, and nonpolar solutes favour nonpolar solvents rather than water.
“Aqueous” does not mean dilute
The word says only that the solvent is water. A water-based solution can be dilute or concentrated, up to the solubility limit of the solute, and the OpenStax chapters cited below set no concentration threshold for the term.
Rubbing alcohol is not a “non-aqueous” label
2-Propanol is a useful example of a non-water solvent, but a commercial product containing it may also contain water. Whether a specific product is aqueous or non-aqueous depends on its stated composition, not on the name of one ingredient.
FAQ
What is meant by aqueous solution in chemistry?
A solution in which water is the solvent, with one or more solutes dissolved in it.
What is a non-aqueous solution?
A solution whose solvent is not water, such as 2-propanol as the solvent in rubbing alcohol.
Are all substances soluble in water?
No. Some ionic compounds are classed as insoluble, and nonpolar solutes generally favour nonpolar solvents.
Is liquid the same as aqueous?
No. Liquid is a state of matter; aqueous means the solvent is water. Solutions can also be gases or solids.
Sources
- OpenStax, Chemistry 2e, 11.1 The Dissolution Process (checked 2026-10-29).
- OpenStax, Chemistry 2e, 11.3 Solubility (checked 2026-10-29).
- OpenStax, Chemistry 2e, 4.2 Classifying Chemical Reactions (checked 2026-10-29).
