Reading pH involves understanding the pH scale and the method used to measure it. The pH scale ranges from 0 to 14, with 7 being neutral. A pH below 7 indicates acidity, while a pH above 7 indicates alkalinity (basicity). This is a measure of the relative amount of free hydrogen and hydroxyl ions in a substance.
Measuring pH
Several methods exist for determining pH:
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pH Test Strips (Litmus Paper): These strips change color when dipped into a solution, indicating the pH level. Match the strip's color to the color chart provided to determine the pH value. Learn more about using pH strips on wikiHow. Ensure your strips cover the pH range relevant to your testing needs. Testing urine or saliva requires dipping the strip in the fluid until both pads are saturated.SimplexHealth offers instructions on urine pH testing.
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pH Meters: These electronic devices provide a precise digital reading of pH. They require calibration before use to ensure accurate measurements.
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pH Indicators: Certain chemical compounds change color based on pH, allowing visual determination of pH within a specific range.
Interpreting pH Values
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pH 7: Neutral; neither acidic nor alkaline. Pure water has a pH of 7.
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pH < 7: Acidic; the lower the number, the stronger the acid. Examples include lemon juice (pH ~2) and stomach acid (pH ~1.5 - 3.5).
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pH > 7: Alkaline (basic); the higher the number, the stronger the base. Examples include baking soda (pH ~9) and household ammonia (pH ~11).
The USGS provides a clear explanation of the pH scale and its implications for water acidity/basicity. See their pH scale visual. Remember that different methods of pH measurement will have different levels of accuracy.
