Problem 64 - Chemistry for Allied Health

Question

A given solution is clear and colorless. A single crystal of solute is added to the solution. Describe what happens in each of the following situations. a. The original solution was saturated. b. The original solution was unsaturated.

Step-by-Step Solution

Answer

a. The crystal remains undissolved. b. The crystal dissolves.

Step 1: Understanding Saturated Solution

A saturated solution has the maximum amount of solute dissolved in it at a given temperature. When additional solute is added, it won't dissolve and will likely remain as a solid in the solution.

Step 2: Result for Saturated Solution

Since the original solution was saturated, adding a single crystal of solute will not dissolve into the solution. It will remain undissolved, as the solution cannot hold any more solute.

Step 3: Understanding Unsaturated Solution

An unsaturated solution has less solute dissolved than it can potentially hold at a given temperature. Thus, it has the capacity to dissolve additional solute.

Step 4: Result for Unsaturated Solution

If the original solution was unsaturated, the added single crystal of solute will dissolve completely until the solution approaches saturation.

Key Concepts

Solution Chemistry

Solution chemistry involves the study of how substances, called solutes, dissolve in a liquid, known as a solvent, to form a solution. In this process, molecules or ions disperse uniformly within the solvent. Solutions can be homogeneous, meaning the solute is evenly distributed, making the solution appear clear and uniform.

One of the key factors in solution chemistry is the concept of saturation. This is determined by the amount of solute that can dissolve at a particular temperature. If a solution is at its maximum capacity of solute, it is considered saturated. Any added solute will remain undissolved, creating a dynamic equilibrium where the rate of dissolution equals the rate of crystallization.

On the other hand, if more solute can be dissolved, the solution is unsaturated. In this case, added solute will readily dissolve until the saturation point is reached. Understanding the state of a solution helps predict how it will react to changes, such as adding more solute or altering temperature.

Crystal Solute Interaction

When a crystal of solute is introduced into a solution, a fascinating process begins. The solute particles in the crystal interact with the solvent molecules surrounding them in what's known as solvation.

These interactions depend significantly on whether the solution is saturated or unsaturated. In a saturated solution, additional solute particles generally bond more strongly with each other than with the solvent, causing them to remain solid instead of dissolving.

In contrast, an unsaturated solution allows for more interactions between solute particles and solvent molecules. This results in the dissolution of the solute crystal as the forces between the solute and solvent overcome those within the crystal. This process continues until the solution becomes saturated.

The nature of these crystal solute interactions plays a crucial role in determining whether a solute will dissolve or precipitate, a concept that provides insight into various applications in pharmaceuticals, food science, and environmental chemistry.

Solubility Concepts

Solubility refers to the ability of a solute to dissolve in a solvent to form a homogeneous mixture. It is an essential concept for understanding how different substances interact in solution chemistry.

A crucial factor influencing solubility is temperature. Typically, solubility increases with temperature, allowing more solute to dissolve. However, this relationship can vary depending on the solute-solvent pair. Some gases become less soluble as temperature rises, which is an important consideration in aquatic environments and industrial processes.

Solubility also involves the concepts of saturation, supersaturation, and concentration. Saturated solutions contain the maximum amount of dissolved solute, whereas unsaturated solutions can still dissolve more. A supersaturated solution holds more solute than typical at a specific temperature, often created by changing conditions like cooling a saturated solution slowly.

Understanding these solubility concepts helps in identifying the behavior of solutions under different conditions, vital for various scientific and industrial applications.