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Kids in the Creek - Water Quality - pH Levels
pH levels
The concentration of hydrogen ions in a solution is
called pH and determines whether a
solution is acid or alkaline. A pH value shows the
intensity of acid or alkaline conditions. In general,
acidity is a measure of a substance's ability to neutralize
bases, and alkalinity is a measure of substance's ability
to neutralize acids.
The pH scale ranges from 1 (acid) to 14 (alkaline or basic)
with 7 as neutral. The scale is logarithmic so a
change of one pH unit means a tenfold change in
acid or alkaline concentration. A change from 7 to
6 represents 10 times the concentration, 7 to 5,
100 times, and so on.
pH Fact Sheet
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State Standards Class AA (Extraordinary) | 6.5 - 8.5
| | Class A (Excellent) | 6.5 - 8.5 |
| Class D (Good) | 6.5 - 8.5 |
| Class C (Fair) | 6.5 - 9.0 |
(Source: WAC 173-201A-030)
Factors that affect pH level values
- Air pollution, primarily from automobile exhaust and fossil fuel burning increase concentrations of sulfur and nitrogen oxides in the air. Therefore when it rains these particles or components turn it to "acid rain" and increase the acidity of lakes and streams.
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Runoff that contains wastewater from farms, logging or mining sites, and other commercial and residential developments sends chemicals and other constituents that alter pH levels.
pH Value Scale
This scale represents the effect various pH levels have on aquatic life.
Notice on the top of the scale how aquatic organisms have a fairly narrow range of tolerance before they die.
Underneath the scale are substances you may be familiar with, and where these fit on the scale as well. (Source: "The Stream Scene")
pH Test
This test measures how acid or how alkaline (base) the water is. A low pH number means the water is acid, a high number means that the water is alkaline. A pH of 7 means that the water is neutral.
Step 1:
Fill one of the glass color viewing tubes to the 5 ml mark water sample.
Step 2:
Add six (6) drops of WIDE RANGE 4 pH INDICATOR SOLUTION to one of the tubes and swirl to mix.
Step 3:
Insert the prepared sample in the right opening of the color comparator.
Step 4:
Insert the tube of original water sample in the left opening of color comparator.
Step 5:
Hold color up to the light, and view through the two openings in the front. Rotate the color wheel until a color match is obtained. Read the pH through the scale window. Record your readings on your data sheet.
Water Quality: pH Levels | Temperature | Dissolved Oxygen
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