What Is a Solute? Solute Definition and Examples   Recently updated !


The solute is the chemical that dissolves in a solvent to form a solution.
The solute is the chemical that dissolves in a solvent to form a solution. (photo: Polina Tankilevitch)

In chemistry, a solute is the substance dissolved in a solvent or the part of a chemical solution present in the smaller amount. Mixing a solute and a solvent resulting in dissolving the solute, which is also known as solvation. Concentration describes the amount of solute in a solvent or solution. For example, the concentration 0.1M HCl describes a solution consisting of 0.1 moles of hydrochloric acid per liter of solution.

The term “solute” comes from the Latin word solvere, which means “to loosen.” The words “solvent” and “dissolve” also derive from the same word.

While solutes are most often discussed in liquid solutions, they also occur in gases and solids.

Solute Properties

A solute displays characteristic properties in a solution:

  • The distribution of a dissolve solute is homogeneous. That is, the number of solute particles per volume is the same, no matter where a solution is sampled.
  • Solute particles are not visible to the eye.
  • The solute in a solution does not scatter light.
  • Solute particles do not settle out of solution and cannot be separated from a solution by filtration.
  • In a solution, the solute is in the same phase as the solvent.

How to Tell Which Is Solute and Which Is Solvent

The solute is the part of a solution present in a lower amount than the solvent. If you know the composition of the solution, it’s easy to identify the solvent, since it accounts for the largest fraction. The remainder of the solution consists of the solute. There may be more than one solute in a solution.

In a chemical reaction, the solute is present in a smaller mole fraction and dissolves in the solvent. Any time you see the symbol (aq) following a chemical species, you know it is a solute in aqueous solution (water).

Solute Examples

Here are examples of solutes:

SoluteSolutionType of SolutionSolvent
SaltSeawaterSolid dissolved in liquidWater
Sugar, dissolved carbon dioxideSodaSolid and gas dissolved in liquidWater
Oxygen, water vapor, carbon dioxide, argonAirGas dissolved in gasNitrogen
ChromiumStainless SteelSolid dissolved in solidIron
NaOH (sodium hydroxide)1.0M NaOH (aq)Solid dissolved in liquidWater
EthanolBeerLiquid dissolved in liquidWater
Acetic acidVinegarLiquid dissolved in liquidWater
Ethane, propane, butaneNatural gasGas dissolved in gasMethane
Silver, copper, indiumDental amalgamSolid dissolved in solidMercury
Examples of solutes and their solutions

Predicting Whether a Solute Will Dissolve

Solubility is a measure of how much of a solute will dissolve in a solvent. Generally, polar solvents dissolve polar solutes, while nonpolar solvents dissolve nonpolar solutes. For example, salt (polar) dissolves in water (polar), but not in oil (nonpolar). Solubility depends on several factors, including temperature, pressure, and the presence of other substances. For example, more salt will dissolve in boiling water than in ice water.

References

  • Clugston, M.; Fleming, R. (2000). Advanced Chemistry (1st ed.). Oxford: Oxford Publishing.
  • Hefter, G.T.; Tomkins, R.P.T (ed.) (2003). The Experimental Determination of Solubilities. Wiley-Blackwell. ISBN 978-0-471-49708-0.
  • Houk, C.; Post, R. (eds.) (1997). Chemistry, Concept and Problems. John Wiley & Sons. ISBN 978-0-471-12120-6.
  • IUPAC (1997). “Solute.” Compendium of Chemical Terminology (2nd ed.) (the “Gold Book”). Compiled by A. D. McNaught and A. Wilkinson. Blackwell Scientific Publications. Online version (2019-) created by S. J. Chalk. ISBN 0-9678550-9-8. doi:10.1351/goldbook

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