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15.4: Solute and Solvent

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    53840
  • In the winter, the temperature often gets well below the freezing point of water. This condition can create problems in car radiators. If the water freezes, water hoses will break, the engine block can crack, and significant damage can be done to the car.

    Solute and Solvent

    When one substance dissolves into another, a solution is formed. A solution is a homogeneous mixture consisting of a solute dissolved into a solvent. The solute is the substance that is being dissolved, while the solvent is the dissolving medium. Solutions can be formed with many different types and forms of solutes and solvents.

    We know of many types of solutions. Check out a few examples in the table below.

    Type Solvent Solute Example
    Table 15.4.1: Types of Solutions
    gas/gas nitrogen oxygen air
    gas/liquid water carbon dioxide soda pop
    liquid/liquid water ethylene glycol antifreeze
    solid/liquid water salts seawater

    We want to focus on solutions where the solvent is water. An aqueous solution is water that contains one or more dissolved substances. The dissolved substances in an aqueous solution many be solids, gases, or other liquids. Some examples are listed in the table above. Other examples include vinegar (acetic acid in water), alcoholic beverages (ethanol in water), and liquid cough medicines (various drugs in water).

    Figure 15.4.1: Typical solution - clear and stable.

    In order to be a true solution, a mixture must be stable. When sugar is fully dissolved into water, it can stand for an indefinite amount of time and the sugar will not settle out of the solution. Further, if the sugar-water solution is passed through a filter it will be unchanged. The dissolved sugar particles will pass through the filter along with the water. This is because the dissolved particles in a solution are very small, usually less than \(1 \: \text{nm}\) in diameter. Solute particles can be atoms, ions, or molecules, depending on the type of substance that has been dissolved.

    Summary

    • A solution is a homogeneous mixture of a solute in a solvent.
    • A solute is the material present in the smaller amount in the solution.
    • A solvent is the material present in the larger amount in the solution.

    Contributors

    • CK-12 Foundation by Sharon Bewick, Richard Parsons, Therese Forsythe, Shonna Robinson, and Jean Dupon.