What term describes a solution that has more solute than it can dissolve?

A saturated solution is a chemical solution containing the maximum concentration of a solute dissolved in the solvent. The additional solute will not dissolve in a saturated solution.

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Factors Affecting Saturation
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The amount of solute that can be dissolved in a solvent to form a saturated solution depends on a variety of factors. The most important factors are:

Temperature: Solubility increases with temperature. For example, you can dissolve much more salt in hot water than in cold water.
Pressure: Increasing pressure can force more solute into solution. This is commonly used to dissolve gases into liquids.
Chemical Composition: The nature of the solute and solvent and the presence of other chemicals in a solution affects solubility. For example, you can dissolve much more sugar in water than salt in water. Ethanol and water are completely soluble in each other.

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You encounter saturated solutions in daily life, not just in a chemistry lab. Also, the solvent does not need to be water. Here are some common examples:

A soda is a saturated solution of carbon dioxide in water. This is why, when the pressure is released, carbon dioxide gas forms bubbles.
Adding chocolate powder to milk so that it stops dissolving forms a saturated solution.
Salt can be added to melted butter or oil to the point where the salt grains stop dissolving, forming a saturated solution.
If you add enough sugar to your coffee or tea, you can form a saturated solution. You'll know you've reached the saturation point when the sugar stops dissolving. Hot tea or coffee allows much more sugar to be dissolved than you can add to a cold beverage.
Sugar can be added to vinegar to form a saturated solution.

If one substance will not dissolve into another, you cannot form a saturated solution. For example, when you mix salt and pepper, neither dissolves in the other. All you get is a mixture. Mixing oil and water together will not form a saturated solution because one liquid does not dissolve in the other.

There's more than one way to make a saturated solution. You can prepare it from scratch, saturate an unsaturated solution, or force a supersaturated solution to lose some solute.

Add solute to a liquid until no more dissolves.
Evaporate solvent from a solution until it becomes saturated. Once the solution starts to crystallize or precipitate, the solution is saturated.
Add a seed crystal to a supersaturated solution so extra solute will grow onto the crystal, leaving a saturated solution.

The definition of a supersaturated solution is one which contains more dissolved solute than could ordinarily dissolve into the solvent. A minor disturbance of the solution or introduction of a "seed" or tiny crystal of solute will force crystallization of excess solute. One way supersaturation can occur is by carefully cooling a saturated solution. If there is no nucleation point for crystal formation, the excess solute may remain in solution.

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When solid solute (substance or particles) and liquid solvent are mixed, the only possible reactions are dissolution and crystallization.

Dissolution is the dissolving process of the solid solute.
Crystallization is the opposite, causing the solid solute to remain undissolved.

Kinds of Saturation	Definition
Saturated Solution	A solution with solute that dissolves until it is unable to dissolve anymore, leaving the undissolved substances at the bottom.
Unsaturated Solution	A solution (with less solute than the saturated solution) that completely dissolves, leaving no remaining substances.
Supersaturated Solution	A solution (with more solute than the saturated solution) that contains more undissolved solute than the saturated solution because of its tendency to crystallize and precipitate.

Example 1: Saturated Solution

Example 1: Above is illustrated an example of a saturated solution. In Figure 1.1-1.3, there is a constant amount of water in all the beakers. Figure 1.1 shows the start of the saturation process, in which the solid solute begins to dissolve (represented by red arrows). In the next beaker, Figure 1.2, much of the solid solute has dissolved, but not completely, because the process of crystallization (represented by blue arrows) has begun. In the last beaker, Figure 1.3, only a small amount of the solute solvent remains undissolved. In this process, the rate of the crystallization is faster than the rate of dissolution, causing the amount of dissolved to be less than the amount crystallized.

Example 2: Unsaturated Solution

Example 2: Next, an unsaturated solution is considered. In Figure 2.1-2.3, there is a constant amount of water in all the beakers. Figure 2.1 shows the start of the process, in which solid solute is beginning to dissolve (represented by red arrows). In the next beaker, shown in Figure 2.2, a large amount of solute has dissolved. The size of the red arrows are much larger than those of the blue arrows, which means that the rate of dissolution is much greater than rate of crystallization. In the last beaker, shown in Figure 2.3, the solute solvent has completely dissolved in the liquid solvent.

Example 3: Supersaturated Solution

Example 3: This is an example of a supersaturated solution. In Figure 3.1-3.3, there is a constant amount of water in all the beakers. Figure 3.1 shows a beaker with more solid solute than in the saturated solution (Figure 1.1) dissolving. In Figure 3.2, solid begins to crystallize as it slowly decreases the rate of dissolution. In the last picture, Figure 3.3, the solids become a crystallized form which begins to harden.

Factors Affecting Saturation

The solubilities of ionic solutions increase with an increase in temperature, with the exceptions of compounds containing anions.
Finely divided solids have greater solubilities.
In contrast to the solubility rate, which depends primarily on temperature, the rate of crystallization depends on the concentration of the solute at the crystal surface.
In a still solution, concentration builds at the solute surface causing higher crystallization; therefore, stirring the solution prevents the build up, maximizing the net dissolving rate.
The net dissolving rate is defined as the dissolving rate minus the crystallization rate.
If the rates of solubility and crystallization are the same, the solution is saturated, and dynamic equilibrium is reached.
Le Chatelier's principle predicts the responses when an equilibrium system is subjected to change in temperature, pressure or concentration. This principle states the following:
- For an increase of temperature, solubility increases which causes an endothermic reactions.
- For an decrease of temperature, solubility decreases which causes an exothermic reactions.
- Adding an inert gas to a constant-volume equilibrium mixture has no effect on the equilibrium.
- An increase in the external pressure causes a decrease in reaction volume and shifts equilibrium to the right.