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Chemical Properties of Water & Water Analysis Chemical Properties of Water CHEMICAL: defined as… [Princeton U.] relating to or used in chemistry; produced by or used in a reaction involving changes in atoms or molecules of or made from or using substances produced by or used in reactions involving atomic or molecular changes. Chemical Properties of Water 5 Key Factors: Oxygen CO2 Temperature pH Hardness OXYGEN (Dissolved O2) Dissolved (DO): Oxygen The amount of free (not chemically combined) oxygen dissolved in water Most aquatic organisms depend on DO as their O2 source OXYGEN (Dissolved O2) Sources: From water turbulence (waves, waterfalls, splashing on rocks, etc.) From plants & algae (photosynthesis) From diffusion from air OXYGEN (Dissolved O2) Solubility of Oxygen: Depends on temperature of water the colder the water, the more O2 it can dissolve (see figure 5.1 pg.85 Blue Book) Temp oC Solubility (μg/g) 0 5 10 15 20 25 30 14.6 12.7 11.3 10.1 9.1 8.3 7.5 OXYGEN (Dissolved O2) The Need for O2: Aquatic species require different amounts of DO Trout, whitefish & walleye = high DO Carp, sunfish & catfish = low DO Knowing what you know… Where would you fish for carp? For trout? OXYGEN (Dissolved O2) Factors that Remove O2: Thermal Pollution Respiration (especially bacteria) Algal blooms Fecal Bacteria Carbon Dioxide (CO2) Need for CO2: - for photosynthesis Source of CO2: - from the air - from respiration Removed By: - plants - turbulence Temperature Directly related to DO levels Increase temp. = lower DO, higher algae growth, etc. (eutrophication) pH pH Scale: A measure of acidity (or alkalinity) Range of 0-14 (0-7 Acidic, 7-14 basic) 6.7–8.6 is desirable for fish (see fig.5-4 text) pH Eutrophication & pH: As a lake ages, its pH will change over time. Acid rain, pollution & sewage can alter pH Oligotrophic Mesotrophic Eutrophic Slightly Acidic or Basic More acidic More Basic Hardness Caused by minerals in the water (calcium & magnesium) Importance: Supports living things, affects human health, economic concerns. LAB: Water Analysis You have obtained 3 samples of water – from 3 very different sources. Using the test kits, test the chemical properties of these water samples 1 per group. Fill in the chart to record data from 3 groups. Now hypothesize the source of these samples! Get to it – The End!!