Dissolve Definition in Chemistry

tablet dissolving in glass of water
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In chemistry, to dissolve is to cause a solute to pass into a solution. Dissolving is also called dissolution. Typically, this involves a solid going into a liquid phase, but dissolution can involve other transformations as well. For example, when alloys form, one solid dissolves into another to form a solid solution.

Specific criteria must be met for a process to be considered dissolution. For liquids and gases, the substance that dissolves must be capable of forming non-covalent interactions with the solvent. For crystalline solids, the crystal structure needs to be broken up to release atoms, ions, or molecules. When ionic compounds dissolve, they separate into their component ions in the solvent.

The term solubility refers to how readily a substance dissolves in a specific solvent. If dissolution is favored, the substance is said to be soluble in that solvent. In contrast, if very little solute dissolves, it is said to be insoluble. Keep in mind, a compound or molecule may be soluble in one solvent yet insoluble in another. For example, sodium chloride is soluble in water but not as soluble in organic solvents such as acetone or turpentine.

Examples

Stirring sugar into water is an example of dissolving. The sugar is the solute, while the water is the solvent.

Dissolving salt in water is an example of dissolution of an ionic compound. The sodium chloride (salt) dissociates into sodium and chloride ions when it is mixed with water.

Releasing the helium from a balloon into the atmosphere is also an example of dissolving. The helium gas dissolves into the larger volume of the air.