In basic science, a mixture is a physical blend of two or more substances that preserve their identities and are blended in the form of solutions, suspensions, or colloids.
A mixture is formed when two or more different substances are combined physically, but they are not chemically bonded together. This means that each substance in the mixture retains its own properties, unlike in a chemical compound where substances lose their original properties.
Key Characteristics of Mixtures
Understanding what makes something a mixture is fundamental. The defining features include:
- Physical Combination: Substances are simply mixed together physically, not chemically reacted.
- Preserved Identities: Each original substance (component) keeps its individual properties (like melting point, color, taste, etc.).
- Variable Composition: The ratio of the substances in a mixture can vary. For example, saltwater can be very salty or just slightly salty.
- Separable by Physical Means: The components of a mixture can often be separated using physical methods such as filtration, evaporation, magnetism, or distillation, because no chemical bonds were formed.
Forms of Mixtures
According to the reference, mixtures can exist in various forms depending on how the substances are blended and the size of the particles involved. These common forms are:
H3 Solutions
Solutions are a type of homogeneous mixture where one substance (the solute) is dissolved completely into another substance (the solvent). The particles are very small and evenly distributed throughout the mixture.
- Examples:
- Salt dissolved in water
- Sugar in tea
- Air (a mixture of gases)
- Alloys like brass (copper and zinc)
H3 Suspensions
Suspensions are heterogeneous mixtures where solid particles are dispersed in a liquid or gas, but they are large enough to settle out over time if left undisturbed.
- Examples:
- Sand in water
- Muddy water
- Some types of liquid medicines (often labeled "shake well")
H3 Colloids
Colloids are also heterogeneous mixtures, but the dispersed particles are larger than those in a solution and smaller than those in a suspension. They do not settle out and often appear cloudy or opaque. Colloids can exhibit the Tyndall effect (scattering of light).
- Examples:
- Milk
- Fog
- Smoke
- Jelly
Comparing Mixture Types
Here is a simple table summarizing the main differences between these forms:
| Feature | Solution | Suspension | Colloid |
|---|---|---|---|
| Homogeneity | Homogeneous | Heterogeneous | Heterogeneous |
| Particle Size | Very small | Large | Medium |
| Settling | No settling | Settles out over time | No settling |
| Transparency | Transparent | Opaque/Cloudy | Opaque/Cloudy |
| Tyndall Effect | No | No (or difficult to see) | Yes |
| Filtration | Cannot be filtered | Can be filtered | Cannot be filtered |
In essence, understanding mixtures is key to distinguishing physical changes from chemical changes in the world around us.
