The Difference Between Colloid and Suspension
When it comes to studying materials, the two terms that can sometimes cause confusion are colloid and suspension. They both refer to a mixture of substances, but they differ in their properties and the way they behave. Below is an explanation of what differentiates colloids from suspensions.
What is a Colloid?
A colloid is a homogeneous mixture of two or more substances where at least one of the substances is in the form of tiny particles spread throughout another substance. The tiny particles in a colloid are smaller than those in a suspension, and they cannot be separated by filtration or centrifugation. Colloidal particles measure between 1 and 1000 nanometers (10-9 meters) in size, so they are not visible to the naked eye.
One important characteristic of colloids is that they can scatter light. This is why milk looks white and why a projector screen reflects light. Colloids can also show the properties of both a solid and a liquid, depending on the conditions. Examples of colloids include milk, blood, and ink.
What is a Suspension?
A suspension is a heterogeneous mixture of two or more substances where solid or liquid particles are suspended in a fluid. Suspensions are not evenly mixed, and larger particles can settle out over time, giving them a cloudy or opaque appearance. Suspensions can be separated by filtration or centrifugation.
The particles in a suspension are much larger than those in a colloid, measuring at least 1000 nanometers in size. Examples of suspensions include muddy water, blood clots, and dust in the air.
The Key Differences Between Colloids and Suspensions
The main differences between colloids and suspensions are:
– Size of particles: Colloidal particles are smaller than those in a suspension.
– Homogeneity: Colloids are homogeneous (uniform throughout), while suspensions are heterogeneous (not uniform).
– Separation: Colloids cannot be separated by filtration or centrifugation, while suspensions can be separated.
– Light scattering: Only colloids can scatter light.
In conclusion, the key differences between colloid and suspension lie in the size of their particles, their homogeneity, and their ability to scatter light. Understanding the properties of each will help in identifying and categorizing materials more accurately.
Table difference between colloid and suspension
| Property | Colloid | Suspension |
|---|---|---|
| Particle size | 1-1000 nm | More than 1000 nm |
| Visibility | Not visible with the naked eye | Visible with the naked eye |
| Settling rate | Slow | Fast |
| Appearance | Homogeneous | Heterogeneous |
| Filterability | Not filterable through ordinary filter paper | Filterable through ordinary filter paper |
| Tyndall effect | Visible | Not visible |