Are colloids heterogenous mixtures or homogenous mixtures?

Question

I am currently in a chemistry 101 class and my professor adamantly believe that colloids fall under heterogenous mixtures only . I have researched on a few definitions of colloids and some sources say that it is a heterogenous mixture, others say its a homogenous mixture. And some even say that it is both. Even the wikipedia source is confusing because under colloids it is considered a heterogenous mixture but when you look at the definition of mixtures and the different kinds, colloids (or colloidal dispensions are referred to as homogenous) fall under homogenous mixture. So if it is both, what then makes a colloid a homogenous mixture and a heterogenous mixture? Thanks!

Answer 1

It depends on the scale you're interested in. If you go small enough, even salt water is heterogeneous, made of sodium ions and chlorine ions, each surrounded by water.

However, most colloids have particles vastly larger a sodium ion, so they can generally be classified as heterogeneous, whereas salt water can be classified as homogeneous.

Answer 2

A colloid is somewhere in between a truly homogenous and heterogenous mixture. At the microscopic level, a colloid is heterogenous. At the macroscopic level it is homogenous.

Macroscopically, a colloid shows a single "phase": if you sample a few micro liters anywhere, it will always have the same composition. But if you look at the microscopic level, you will find that there are at least two different regions, each with a different composition.

What you should follow is dependent on whether the macroscopic or microscopic properties matter more to what you are studying.

Answer 3

Colloidal Mixture

Answer 4

Colloids are mixtures whose particles are larger than the size of a molecule but smaller than particles that can be seen with the naked eye. Colloids are one of three major types of mixtures, the other two being solutions and suspensions. The three kinds of mixtures are distinguished by the size of the particles that make them up. The particles in a solution are about the size of molecules, approximately 1 nanometer (1 billionth of a meter) in diameter. Those that make up suspensions are larger than 1,000 nanometers. Finally, colloidal particles range in size between 1 and 1,000 nanometers. Colloids are also called colloidal dispersions because the particles of which they are made are dispersed, or spread out, through the mixture.

Answer 5

Not only fat globules, but also little islands of protein. Milk without all the suspended stuff is called whey and is also referred to as milk plasma. Since the protein islands in the skim mild cannot be distributed evenly. this means that it is a heterogeneous mixture, but since it is stable and the little islands do no settle out, it is a colloidal dispersion.

Answer 6

The main criterion for determining if a mixture is homogeneous is if it can be mechanically separated. Colloids can be filtered through fine membranes, so that is why they're not considered homogeneous mixtures.

Answer 7

a colloid is heterogenous, reason being that the components are separtely visible and the mixture is not cleare, it scatters light rays

Answer 8

It is a type of heterogeneous mixture.