Hands-on Activity: Messin' with Mixtures
Educational Standards :
Learning Objectives (Return to Contents)
After this activity, students should be able to:
Materials List (Return to Contents)
Each group needs:
For the class to share:
Introduction/Motivation (Return to Contents)
Today we are going to talk about mixtures and solutions. A mixture is made up of two or more kinds of matter, but sometimes you can still see the different components, like sand and water. A solution is a special type of mixture where you cannot tell the difference between the components, and it cannot be separated easily.
What are some other differences between a mixture and solution? Well, mixtures retain their original properties, and solutions do not. In most cases, a solution has different properties than the two or more parts that went into making it. Also, solutions are the combination of a solute and a solvent. For example, in salt water, the salt is a solute and water is the solvent. Is it possible to separate the different substances in a solution? The answer is yes. In salt water, the two parts of the solution may be separated by evaporation. Other times it may be as easy as using a filter or a screen.
Who can think of another example of a mixture or solution? (Have students list answers such as, bubble mix, lemonade, milk, etc.) What is the difference between milk and Italian salad dressing? (Possible answers include: difference in color, the milk is the same throughout the whole bottle while the dressing separates after it sits for a bit.) Mixtures and solutions that are the same throughout (like milk, Kool-Aid®, etc) are called homogenous. Ones that are not consistent throughout (like Italian salad dressing, oil and water, etc.) are heterogeneous. Heterogeneous mixtures and solutions are normally much easier to separate. Filtering is an easy way to separate heterogeneous mixtures. Large rocks can easily be separated from small rocks and sand. It is much harder to separate the individual parts of Kool-Aid® (water, sugar, Kool-Aid® packet mixture).
Why would an engineer care about mixtures and solutions? Well, engineers design ways to help separate mixtures and solutions in industrial, commercial and environmental processes. Can you think of any engineers that have worked with the mixtures or solutions we listed a minute ago? Chemical engineers work with the foods we encounter every day. They need to know what chemicals are safe to mix with foods when designing fertilizers and preservatives to keep food healthy for us to eat. Another example is environmental engineers working with acid mine drainage. Acid mine drainage is when metals from mining sites break down into the surrounding ground water and surface waters. This water from the mining area can become acidic and discolored, and disrupt the surrounding stream ecosystems. These areas can also be a health concern to humans who use the same groundwater resources. Engineers work on cleaning up the mixtures and solutions of metals and bacteria in acid mine drainage areas as well as streams, drinking water, air and soils. Engineers use knowledge of mixtures and solutions to help create environmental policies, and design water treatment processes, ways to help the environment, and new medicines to help people.
In this activity, we are going to look at a heterogeneous mixture as if it were a contaminated soil sample to be cleaned up by environmental engineers. We will separate the mixture by filtration and then create a solution using M&M® candies. Are you ready?
Vocabulary/Definitions (Return to Contents)
Procedure (Return to Contents)
Before the Activity
Prepare the materials and copy the Soil Sleuths worksheet.
With the Students
Attachments (Return to Contents)
Troubleshooting Tips (Return to Contents)
Be sure to have the trail mix in bags and the worksheets copied. Go over the directions and worksheet before the students attempt this activity. Be sure to give instructions before you pass out the candy.
Assessment (Return to Contents)
Discussion Questions: Solicit, integrate and summarize student responses.
Activity Embedded Assessment
Worksheet: Have the students complete the Messin' Around Worksheet; review their answers to gauge their mastery of the subject.
Engineering Application: Have the students write a "report" for the construction company that was working the site where the contaminated soil was found. They should include in their report: if the soil was highly contaminated, what percent of contaminants was found in the soil, why these contaminants should be removed, and a recommendation for how their engineering firm might remove the contaminants from the soil for the construction company. (The last part is creative writing, since only filtering was focused on in the activity.)
Graph it! As an extra math extension, have students create a pie chart of their percentages from Part 1.
Activity Extensions (Return to Contents)
Have the students discuss how they could turn the trail mix bag into a solution. Allow student to write down their steps for completing this task and share their ideas with the class.
Have students research types of soil, water or air contamination. Have them report back to the class on what engineering processes have been developed for cleaning up these types of contamination, including bioremediation and electromechanical processes.
Have the students complete the oil spill activity in TeachEngineering.com. This activity has students create a model oil spill and discuss strategies for separating the oil from the water, a heterogeneous mixture.
Activity Scaling (Return to Contents)
For lower grades, do not use the Soil Sleuths Worksheet, only use observation techniques. Have the students make a list of things they learned, including differences and similarities of mixtures and solutions.
References (Return to Contents)
Trimpe, Tracy. Science Spot, Chemistry Lesson Plans, September 4, 2006, accessed September 7, 2006. http://www.sciencespot.net/Pages/classchem.html#Anchormixtures
ContributorsBrian Kay, Daria Kotys-Schwartz, Malinda Schaefer Zarske, Janet Yowell
Copyright© 2006 by Regents of the University of Colorado
Supporting Program (Return to Contents)Integrated Teaching and Learning Program, College of Engineering, University of Colorado Boulder
Acknowledgements (Return to Contents)
The contents of this digital library curriculum were developed under a grant from the Fund for the Improvement of Postsecondary Education (FIPSE), U.S. Department of Education, and National Science Foundation GK-12 grant no 0338326. However, these contents do not necessarily represent the policies of the Department of Education or National Science Foundation, and you should not assume endorsement by the federal government.