Yes, a solution can indeed be dilute and saturated simultaneously. While these terms might seem contradictory at first glance, they describe different aspects of a solution's composition.
Understanding Saturated vs. Dilute Solutions
Let's break down what these terms mean:
- Saturated Solution: A solution is saturated when it contains the maximum amount of solute that can dissolve in a given amount of solvent at a specific temperature and pressure. If you add any more solute, it will not dissolve and will typically settle at the bottom.
- Dilute Solution: A dilute solution is one that contains a relatively small amount of solute compared to the amount of solvent or compared to the maximum amount that could potentially be dissolved. It implies a low concentration.
The Connection: The Role of Low Solubility
The key factor that allows a solution to be both dilute and saturated is the solubility of the solute. Solubility is a measure of how much solute can dissolve in a given solvent.
As highlighted in the provided reference:
"If a solute has poor, very low solubility, you can have a saturated solution that is very dilute compared to other solute/solvent mixtures. Therefore, a solution can be both dilute and saturated at the same time. The answer is yes."
This means that for substances with very low solubility, the "maximum amount" they can dissolve before the solution becomes saturated is actually quite small. Even though the solution has reached its saturation point (no more solute will dissolve), the total amount of dissolved solute is low, making the solution dilute in terms of overall concentration.
Practical Example
Consider a substance with very low solubility in water, such as silver chloride (AgCl) or lead(II) chloride (PbCl₂).
- If you add a small amount of AgCl to water, very little will dissolve.
- You quickly reach the point where no more AgCl can dissolve – the solution is now saturated.
- However, because the solubility of AgCl is so low, the actual amount of dissolved AgCl in the water is tiny.
- Compared to a saturated solution of a highly soluble substance like table salt (NaCl), the saturated AgCl solution contains a much smaller concentration of solute.
- Therefore, the saturated AgCl solution is also considered dilute.
In essence, a saturated solution simply means the solvent is holding as much solute as it can hold. A dilute solution means the concentration of solute is low. If the solute's solubility is inherently low, the maximum amount it can hold (saturated) will result in a low concentration (dilute).
