Video Transcript
What name is given to a mixture that consists of particles distributed in a medium that will settle to the bottom of the container over time? (A) Saturated solution, (B) suspension, (C) colloid, (D) blended solutions, (E) homogeneous mixture.
Firstly, a mixture is the physical combination of two or more substances in which each substance retains its distinct identity. Mixtures can be classified into several categories. Let’s first focus on the difference between homogeneous and heterogeneous mixtures. When two or more substances combine to form a mixture that has a uniform composition throughout, the mixture is classified as a homogeneous mixture. One way to remember this is knowing that the word part homo- means same, indicating that the composition and properties of the mixture are the same throughout. Another word for a homogeneous mixture is a solution. A mixture that has a nonuniform composition is classified as a heterogeneous mixture. One way to remember this is knowing that the prefix hetero- means different, indicating that the composition and properties of the mixture are different throughout.
In a solution, particles are fully dissolved in a medium, usually referred to as a solvent. In a solution, the dissolved solute particles are individual atoms, ions, or molecules. These particles are far too small to be separated from the solution by filtration. In addition, these particles will not settle to the bottom of the container over time.
To answer this question, we need to identify a mixture in which the particles will settle to the bottom of the container over time. Because we’ve learned that in homogeneous mixtures or solutions the particles will not settle to the bottom of the container over time, we can eliminate answer choices (A), (D), and (E). In a heterogeneous mixture, larger particles are dispersed in a medium, not dissolved. Heterogeneous mixtures are further classified into two types: colloids and suspensions. In colloids, large particles are dispersed in a medium, and colloids often have the appearance of homogeneous mixtures.
However, if we examined a colloid under magnification, we’d be able to see that, in fact, the composition is not uniform. Even though colloids are classified as heterogeneous mixtures, they cannot be separated by filtration. And their dispersed particles do not settle to the bottom of the container. Knowing this allows us to eliminate answer choice (C). The dispersed particles in suspensions are even larger than those found in colloids. If a suspension is continuously agitated or stirred, it may have an appearance of a homogeneous mixture. If left undisturbed for a period of time, the large suspended particles will settle to the bottom of the container. These solid particles can be removed from the suspension by filtration.
In conclusion, the name given to a mixture that consists of particles distributed in a medium that will settle to the bottom of the container over time is a suspension, or answer choice (B).
