A true solution and a colloidal solution differ mainly in particle size, visibility, and properties. Here’s a clear comparison:
Difference between True Solution and Colloidal Solution
- Particle Size
- True Solution: Solute particles are extremely small (< 1 nm).
- Colloidal Solution: Particle size is intermediate (1–1000 nm).
- Visibility of Particles
- True Solution: Particles are invisible, even under a microscope.
- Colloidal Solution: Particles cannot be seen with the naked eye but can be observed under an ultramicroscope.
- Homogeneity
- True Solution: Completely homogeneous; solute and solvent form a single phase.
- Colloidal Solution: Appears homogeneous to the naked eye but is actually heterogeneous (two phases: dispersed phase + dispersion medium).
- Separation
- True Solution: Solute cannot be separated by filtration or centrifugation.
- Colloidal Solution: Colloidal particles cannot be filtered by ordinary filter paper but can be separated by ultrafiltration.
- Tyndall Effect (light scattering)
- True Solution: Does not show Tyndall effect.
- Colloidal Solution: Shows Tyndall effect (scattering of light by particles).
- Stability
- True Solution: Very stable; solute does not settle.
- Colloidal Solution: Quite stable, but particles may coagulate under certain conditions.
- Examples
- True Solution: Sugar in water, salt in water.
- Colloidal Solution: Milk, blood, starch solution, fog.
In short: A true solution is a homogeneous mixture with particles <1 nm that cannot scatter light, while a colloidal solution is a heterogeneous system with particle size 1–1000 nm that shows the Tyndall effect and special stability properties.