Presentation on theme: "PH. What is pH? pH is a measure of the acidity, [H + ], or basicity (alkalinity), [OH - ], of a solution. The scale is typically measured from 0 to 14."— Presentation transcript:
What is pH? pH is a measure of the acidity, [H + ], or basicity (alkalinity), [OH - ], of a solution. The scale is typically measured from 0 to 14. A pH value of 7 is considered to be neutral, neither acid nor base.
What is pH? pH is a logarithmic function. That is, pH = -log10 [H+]. This simply means that a change of one pH unit represents a 10 fold change in the acidity, e.g. pH 5 is ten times more acidic than pH 6.
For the More Advanced Students pH = -log10 [H+] So if: pH = 5 Then 5 = -log 10 [H + ] -5 = log 10 [H + ] 10-5 = [H + ] or [H + ] = 10-5 M
pH levels in our lives Water on the Web http://wow.nrri.umn.edu/wow/
What affects pH? pH can affect and be affected by atmospheric chemistry. –Dissolved CO 2 –Other nonmetallic oxides pH can affect and be affected by geological chemistry. –Dissolved minerals –Other sources of minerals Buffering capacity –Determines the vulnerability of a system to pH changes
Activity: Acids, Bases and Buffers See handout Use of Probes
Acid Mine Drainage Seepage from an historical mine tailing deposition area. Whitewood Valley, South Dakota. USFWS photo by Joy Gober and Scott Larson. http://www.r6.fws.gov/contaminants/contaminants2.html
Why is pH important? Some organisms can tolerate a wider pH range. State Water Resources Control Board-Citizen Monitoring http://www.swrcb.ca.gov/nps/docs/Ph.doc
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