When you add more solute to a saturated solution, the added solute will generally not dissolve. Instead, it will typically settle at the bottom of the container as a solid.
Understanding Saturated Solutions
A saturated solution is one in which the maximum amount of solute has been dissolved in the solvent at a specific temperature and pressure. At this point, the solution cannot hold any more dissolved solute.
As noted in the reference provided, you often know a solution is saturated because it will generally contain some undissolved solid solute already present. This visible solid indicates that the solvent has dissolved all it can.
The Dynamic Equilibrium
In a saturated solution that contains undissolved solid, a state of dynamic equilibrium exists. This means that solute particles are continuously dissolving into the solution, while simultaneously, dissolved solute particles are crystallizing out of the solution back onto the solid. These two processes occur at equal rates, resulting in no net change in the amount of dissolved solute.
Adding More Solute: The Outcome
Since a saturated solution is already holding the maximum possible amount of dissolved solute, adding more solute does not increase the concentration of the solution.
According to the reference, adding more solute to a saturated solution will simply result in more solid at the bottom of the solution. The added solute particles find that there are no available spaces in the solvent to dissolve into, so they join the existing undissolved solid particles.
Here's a simple breakdown of what happens:
- Before Adding Solute: Solution holds the maximum dissolved amount; undissolved solid may be present.
- Adding More Solute: Solute is introduced into the system.
- After Adding Solute:
- The amount of dissolved solute remains constant (at the maximum).
- The concentration of the solution does not change.
- The newly added solute settles as undissolved solid, increasing the amount of solid at the bottom.
Summary of Effects
Let's look at the state of the system before and after adding solute to a saturated solution:
| Aspect | State Before Adding Solute (Saturated) | State After Adding Solute |
|---|---|---|
| Dissolved Solute | Maximum possible amount | Stays at the maximum amount |
| Solution Concentration | Maximum possible | Remains unchanged |
| Undissolved Solute | Often present | Increases (added solute joins the solid) |
In essence, the solution itself doesn't become "more saturated"; it remains saturated, and the excess solute simply remains in its solid form.
