Solutions, Mixtures, and Colloids: Key Concepts in GOB Chemistry

Solutions and Solution Formation

Definition and Properties of Solutions

Solutions are homogeneous mixtures composed of two or more components that form a uniform composition throughout. They are fundamental in chemistry due to their widespread occurrence and importance in chemical reactions and biological systems.

• Solute: The smaller portion of the solution that is dissolved within the solvent.

• Solvent: The part of the solution present in the larger amount, which dissolves other substances.

• Concentration: A measurement of the amount of solute in a given solution.

Example: If 10.0 g NaCl is dissolved in 500.0 mL of water, the solute is 10.0 g NaCl and the solvent is 500.0 mL water.

Solution Formation: The process involves the solute dispersing uniformly within the solvent to form a solution.

Equation for Concentration:

$\text{Concentration} = \frac{\text{Amount of solute}}{\text{Amount of solution}}$

Suspensions vs. Colloids

Classification of Mixtures

Mixtures can be classified based on the uniformity and particle size of their components. The two main types discussed here are suspensions and colloids.

• Suspensions: Heterogeneous mixtures where larger solute particles float in a solvent. These particles are visible and will settle out over time.

• Colloids: Homogeneous mixtures where solute particles are intermediate in size and do not settle out. The particles are not visible to the naked eye but can scatter light (Tyndall effect).

Type	Particle Size	Visibility	Settling	Example
Suspension	Large	Visible	Settles out	Muddy water
Colloid	Intermediate	Not visible	Does not settle	Milk
Solution	Small (ions/molecules)	Not visible	Does not settle	Salt water

Identifying Mixtures by Appearance

Mixtures can often be identified visually based on the distribution and appearance of their components:

• Solution: Clear and uniform throughout.

• Suspension: Cloudy, with visible particles that may settle.

• Colloid: Appears uniform but may scatter light; particles are not visible.

Example: Given images of three containers, one clear (solution), one cloudy with settling particles (suspension), and one cloudy but stable (colloid), you can identify each type based on these properties.

Additional info: The Tyndall effect is a distinguishing property of colloids, where light is scattered by the intermediate-sized particles, making the path of light visible in the mixture.