Final answer:
The concentration of a solution is a measure of the solute dissolved in a solvent, expressed as a ratio of solute mass to solution mass or in moles per unit volume.
Step-by-step explanation:
The concentration of a solution is a key concept in chemistry that describes the amount of solute dissolved in a given amount of solvent or solution. This quantitative measure is essential for expressing how concentrated or dilute a solution is. Concentration can be expressed in various ways, such as mass percentage, parts per million (ppm), or parts per billion (ppb). It is often calculated as the ratio of the mass of the solute to the total mass of the solution.
Another way to describe concentration is mathematically in terms of moles per unit volume. For example, in a typical solution with a solid substance dissolved in a liquid, the moles of solute per unit volume tell us the molar concentration. Terms like dilute or concentrated are relative descriptions that indicate low or high amounts of dissolved solute, respectively. To be precise, percentages may be used, expressing concentration either by mass or volume ratios.