Problem 63 - Chemistry for Allied Health

Question

What are two things that you could do to change an unsaturated solution into a saturated solution?

Step-by-Step Solution

Answer

Add more solute or lower the temperature to turn an unsaturated solution into a saturated one.

Step 1: Understanding Solution Saturation

An unsaturated solution means it still has the capacity to dissolve more solute at a given temperature. A saturated solution cannot dissolve any more solute under the same conditions.

Step 2: Adding More Solute

Add more solute to the unsaturated solution until no more can dissolve. Stir the solution to ensure that the solute is evenly distributed. The point at which no more solute can dissolve indicates that saturation has been achieved.

Step 3: Changing Temperature

Lower the temperature of the solution. Solubility of most solids decreases with a decrease in temperature, which can make a solution saturated with less of the solute. Conversely, heating an unsaturated solution can make it possible for more solute to dissolve, but cooling helps in reaching saturation if the solution is already near its limit.

Key Concepts

Understanding Unsaturated Solutions

In an unsaturated solution, there’s room for more solute. Imagine you're adding sugar to your iced tea. As long as the sugar keeps dissolving, the tea is considered unsaturated.
An unsaturated solution has not reached its limit of solute.

• It can dissolve more solute until reaching saturation.
• The solution remains clear since the added solute completely dissolves.

So, in the case of your iced tea, you can keep adding sugar and stirring until you notice that it starts to settle at the bottom.

Identifying Saturated Solutions

A saturated solution is like a sponge that is completely soaked and can't hold any more water. This means no matter how much more solute is added, it won't dissolve.
For example, let's say you're adding salt to water.

• Once the water can't dissolve any more salt, it becomes saturated.
• Any extra salt will simply collect at the bottom.

In a saturated solution, the solute begins to form crystals if more is added, as there is no room left for it to dissolve.
Reaching saturation can be confirmed when added solute starts to accumulate without dissolving.

Role and Behavior of Solute

The solute is the substance being dissolved, like sugar in our tea analogy. Its behavior is key to understanding solution saturation levels.
The process follows these steps:

• When solute is added, it disperses into the solvent.
• At a certain point, known as the saturation point, the solvent cannot dissolve any more solute.
• Excess solute will remain undissolved at the bottom of the container.

Solubility can depend on several factors:

• Temperature: Higher temperatures often increase solubility for most solids.
• Pressure: For gases, increased pressure can raise solubility.

Understanding how solute interacts with its solvent is crucial for mastering solution concepts.