Mixtures and Solutions

Mixtures

A mixture is a material composed of two or more substances that can be separated by physical means.  A mixture may not be made of the same composition of materials every time, for various reasons.  Of the many example that there are to choose from, one is concrete.  Concrete is made up of sand, Portland cement, an aggregate (rock), and water.  The ratios of these components differ for each type of application for the concrete.  One application may be for yard statuary.  This type of use would not need to be as strong as the concrete used for a highway so more sand and less Portland cement may be used.  If one would need the cement for a highway then more Portland cement and aggregate would be needed and less sand.  The point is that both types of applications still use concrete.  A mixture is considered heterogeneous, in that the materials that make up the mixture is not necessarily uniform throughout and they can be see with the naked eye, or by microscope.

Solutions

In a solution there are at least 2 different compounds mixed together.  A solution is homogenous, in that the compounds that make up the solution are evenly distributed and cannot be seen with the unaided eye or microscope. 

Colloids and Suspensions

A colloid is a heterogeneous mixture that never settles.  In a colloid, the particles are not large enough to see with the naked, unaided eye.  A way to determine if a substance is a solution or colloid is to shine a light through it.  If the light shinning through the material is no scattered, the material is a solution.  Where as if the light scatters, the material is a solution.  The light scatters in a colloid because even though the particles that make it up are not large enough to be seen, they are large enough to bend light as it passes through.

A suspension is like a mixture in that it is a heterogeneous.  In a suspension the particles are large enough so see but they settle.  Think of getting sample of pond water.  You would see al sorts of material and organisms floating in the water.  If left to sit still, the material would settle to the bottom but become mixed once energy was place back into the system like being shaken.

Back        Composition of matter      Phy. Sci. Main Page        Describing Matter