Everything in Chemistry deals with mixtures. As we learned in class today, there are three main types of mixtures found in our world -- Suspensions, Colloids, and Solutions. 99 % of the mixtures that we deal with on a regular basis are solutions.
Key Terms
Solvent - The larger of the two in a mixture, it is often the one doing the "dissolving". If you are at all unsure as to what is the solvent, water is a very solid guess as it is the universal solvent.
Solute - The smaller of the two in a mixture, it is the one that is dissolved in the solution.
Suspension
A suspension is a mixture where the particles are large enough that they can be separated through filtration or settling. The example the book gave was pepper in water and my example was chocolate milk. No matter how much the pepper and water mixture is stirred, it will never mix together and is therefore uneven. In my example the milk will mix with the chocolate but if we let the mixture sit for long enough the chocolate will settle at the bottom of the glass, which is so frustrating.
Key Terms
Solvent - The larger of the two in a mixture, it is often the one doing the "dissolving". If you are at all unsure as to what is the solvent, water is a very solid guess as it is the universal solvent.
Solute - The smaller of the two in a mixture, it is the one that is dissolved in the solution.
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| Photo courtesy of http://media4.onsugar.com |
Suspension
A suspension is a mixture where the particles are large enough that they can be separated through filtration or settling. The example the book gave was pepper in water and my example was chocolate milk. No matter how much the pepper and water mixture is stirred, it will never mix together and is therefore uneven. In my example the milk will mix with the chocolate but if we let the mixture sit for long enough the chocolate will settle at the bottom of the glass, which is so frustrating.
Colloid
A colloid is where the particles are slightly smaller than those in a suspension and are mixed uniformly together. The particles in the mixture are undissolved but do not settle like in a suspension. Some example of a colloid are smoke, fog, milk, and JELLO. The way to tell if a mixture is a colloid or a solution is through the Tyndall Effect which is how the mixture affects a path of light. I will talk more about this at the end of the blog.
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| Liquid JELLO Photo courtesy of www.sundaysugar.com |
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| Fog at Golden Gate Bridge Photo courtesy of kids.britannica.com |
Solution
A solution is a mixture where the mixture is evenly distributed much like a colloid but the solute is dissolved in the solvent. A solution can not be separated through filtration or settling but rather by boiling or evaporating the solvent. An example that we used a lot in class was the mixture of salt and water. Below is a link showing how water dissolves salt to form a solution. It is this polarity of water that makes it the universal solvent.
Tyndall Effect - This is how scientists identify whether a mixture is a colloid or solution. If a light beam is pointed through a solution it will not pass through it while on the other hand if the same light is shot at a colloid it will pass through it. A good example uses a laser pointer. If you point a laser pointer at a wall all you see on the wall is a dot and the beam of light is invisible. If, however, you point that same laser pointer through fog, you are able to see the entire beam of light as well as the point on the wall. See pictures below to for illustration.
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| Laser through air - solution Photo courtesy of www.colorfullighting.net |
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| Laser through fog - colloid Photo courtesy of www.freaklasers.com |
The chart that was put on the board at the end of the class below.
Suspension Colloid Solution
Particle size Large Medium Small
Separation Through filtration/ Does not Through boiling/
settling separate evaporation
Appearance Cloudy Cloudy Clear
Tyndall Effect Yes Yes No
Even/Uneven Uneven Uneven Even
Here is a great video that sums up all we learned. He uses a lot of language that is a little above what we have learned but it will make sense to you guys. You can stop watching after the 10:20 mark.
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