An Aquatic Apocalypse
Millions of fish are dead along a stretch of the White River that passes through Indiana. So what happened? This problem-based unit asks students to complete a series of experiments to determine the possible cause of the fish kill.
This problem-based unit was designed to teach the required objectives for solution chemistry in the state of Texas. It would likely work with or without modification in many other venues.
(A) describe the unique role of water in chemical;
(B) develop and use general rules regarding solubility through investigations with aqueous solutions;
(C) calculate the concentration of solutions in units of molarity;
(D) use molarity to calculate the dilutions of solutions;
(E) distinguish between types of solutions such as electrolytes and nonelectrolytes and unsaturated, saturated, and supersaturated solutions;
(F) investigate factors that influence solubilities and rates of dissolution such as temperature, agitation, and surface area;
(G) define acids and bases and distinguish between Arrhenius and Bronsted-Lowry definitions and predict products in acid base reactions that form water;
(H) understand and differentiate among acid-base reactions and precipitation reactions;
(I) define pH and use the hydrogen or hydroxide ion concentrations to calculate the pH of a solution; and
(J) distinguish between degrees of dissociation for strong and weak acids and bases.
Teacher instructions and keys are included for each activity/ worksheet.
- Introduction – Students learn the basics of the fish kill.
- Solutions Vocabulary – Students define the basic vocabulary for the solutions unit.
- Pollutants and Sources – Students read about possible pollutants and places along the river that might be a source of pollution. Students then “diagnose” 6 scenarios with this information.
- Solubility Rules Part 1 – Students experiment to develop rules of solubility to help determine whether the river water is contaminated with lead, arsenic, or aluminum.
- Solubility Rules Part 2 – Students use their solubility rules to rule out the presence of lead and arsenic in the river water.
- Concentrations and Dilutions – Students calculate the concentration of aluminum in their water and perform a serial dilution.
- Solubility vs. Temperature – Students create a solubility curve for potassium nitrate using experimental data. They use this and other data to determine if phosphates or nitrates contributed to the fish kill.
- Solubility of Gases – Students create a solubility curve for CO2 gas using experimental data. They use this and other data to decide if changes in the water temperature could have reduced dissolved oxygen concentrations in the water.
- Acids and Bases – Students perform a micro-titration to determine the pH of the river water and to determine whether acidity/ alkalinity contributed to the fish kill.
- Summary – Students summarize their findings and decide if there is an obvious source of the pollution.
- Additional Worksheets –
--- WS 1 – Extra vocabulary review – Extension reading
--- WS 2 – Practice working with solubility rules and apply solubility concepts to real world scenarios – Extension reading
--- WS 3 – Practice calculating molarity – Extension reading
--- WS 4 – Practice reading a solubility curve and applying solubility and dissolving rate concepts to real world scenarios – Extension reading
--- WS 5 – More practice reading a solubility curve and applying solubility concepts to real world scenarios – Extension reading
--- WS 6 – Calculating pH from [H+] and [OH-] concentration and applying acid and base concepts to real world scenarios.
See the Preview for a list of materials, a possible calendar, the introduction to the scenario, and the “Solubility vs. Temperature” component.