To increase students' awareness of possible invisible pollutants in drinking water sources, students perform an exciting lab requiring them to think about how solutions and mixtures exist even in unsuspecting places such as ink. They use alcohol and chromatography paper to separate the components of black and colored marker ink. Students witness first-hand how components of a solution can be separated, even when those individual components are not visible in solution.
In this first part of a two-part lab activity, students use triple balance beams and graduated cylinders to take measurements and calculate the densities of several common, irregularly shaped objects with the purpose to resolve confusion about mass and density. After this activity, conduct the associated Density Column Lab - Part 2 activity before presenting the associated Density & Miscibility lesson for discussion about concepts that explain what students have observed.
Concluding a two-part lab activity, students use triple balance beams and graduated cylinders to take measurements and calculate densities of several household liquids and compare them to the densities of irregularly shaped objects (as determined in Part 1). Then they create density columns with the three liquids and four solid items to test their calculations and predictions of the different densities. Once their density columns are complete, students determine the effect of adding detergent to the columns. After this activity, present the associated Density & Miscibility lesson for a discussion about why the column layers do not mix.
After students conduct the two associated activities, Density Column Lab - Parts 1 and 2, present this lesson to provide them with an understanding of why the density column's oil, water and syrup layers do not mix and how the concepts of density and miscibility relate to water chemistry and remediation. Topics covered include miscibility, immiscibility, hydrogen bonds, hydrophobic and hydrophilic. Through the density column lab activities, students see liquids and solids of different densities interact without an understanding of why the resulting layers do not mix. This lesson gives students insight on some of the most fundamental chemical properties of water and how it interacts with different molecules.
Students are introduced to the fundamentals of environmental engineering as well as the global air, land and water quality concerns facing today's environmental engineers. After a lesson and activity to introduce environmental engineering, students learn more about water chemistry aspects of environmental engineering. Specifically, they focus on groundwater contamination and remediation, including sources of contamination, adverse health effects of contaminated drinking water, and current and new remediation techniques. Several lab activities provide hands-on experiences with topics relevant to environmental engineering concerns and technologies, including removal efficiencies of activated carbon in water filtration, measuring pH, chromatography as a physical separation method, density and miscibility.
Students are presented with examples of the types of problems that environmental engineers solve, specifically focusing on air and land quality issues. Air quality topics include air pollution sources, results of poor air quality including global warming, acid rain and air pollution, as well as ways to reduce air pollution. Land quality topics include the differences between renewable and non-renewable resources, the results of non-renewable resource misuse and ways to reduce land pollution. (Water quality is introduced in a later lesson in a separate presentation, as it is the focal point of this unit curriculum.)
Students take advantage of the natural ability of red cabbage juice to perform as a pH indicator to test the pH of seven common household liquids. Then they evaluate the accuracy of the red cabbage indicator, by testing the pH of the liquids using an engineer-designed tool, pH indicator strips. Like environmental engineers working on water remediation or water treatment projects, understanding the chemical properties (including pH) of contaminants is important for safeguarding the health of environmental water sources and systems.
Students measure the effectiveness of water filters in purifying contaminated water. They prepare test water by creating different concentrations of bleach (chlorine-contaminated) water. After passing the contaminated water through commercially available Brita® water filters designed to purify drinking water, students determine the chlorine concentration of the purified water using chlorine test strips and measure the adsorption of chlorine onto activated carbon over time. They graph and analyze their results to determine the effectiveness of the filters. The household active carbon filters used are one example of engineer-designed water purification systems.