Table of Contents Water Quality Testing
pH 8. pH stands for the “power of Hydrogen” and measures the concentration of hydrogen ions in a solution, such as water. What is a hydrogen “ion?” It is an atom of hydrogen that has lost its electron. In water, hydrogen automatically gives up its electron to form ions.
9. pH varies over an enormous range of values. Thus, it has to be measured on a scale that is different from other measurement scales. A solution with a pH=0 has 10 times more hydrogen ions than a solution with a pH=1 and 100 times more hydrogen ions than a solution with a pH=100. This “logarithmic” type of scale is commonly used in chemistry and physics to specify the value of numbers that have an extreme range of values.
10. What affects pH? pH or the concentration of hydrogen ions in water is largely determined by the environment surrounding a lake, river, or stream. Changes in pH can be the result of natural phenomena or man-made events. A change in pH can disrupt the life cycles of all organisms (animals and plants) and lead to their deaths if the change is hydrogen ion concentration is too extreme.
11. Explain the pH scale. Describe that the scale refers to the number of hydrogen ions in a substance and whether or not that substance gives ions in a reaction. A substance that keeps ions is an acid, whereas a substance that takes ions is a base. The scale consists of the numbers 0 to 14, with 0 being the most acidic, 14 being the most basic, and 7 being neutral. Highly acidic water can cause damage to the surrounding environment.
12. Instruct students to place the tip of a piece of pH paper in a sample of surface water from the bucket. To get the most accurate results, they should hold only the edge of the paper and avoid spreading oils from their fingers.
13. After the paper has changed colors, students should compare it to the chart on the pH paper container and record results. Ask them to compare their results with the pH of pure water (7).
14. Post student results on chart paper in the classroom. Ask students to hypothesize about the data. Why are the water temperature, ph, and specific gravity changing? Do you notice any trends in data according to the seasons?
15. Extension Opportunity: Measure the dissolved oxygen and relate it to the marine environment and ecosystem. Students can really relate to animals needing oxygen and getting sick if the levels are not right. Incorporate a seine net to test the biodiversity to see if the water quality parameters are sustainable for life.
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