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Correct Method for a pH Paper Acid & Alkalinity Test

Blue litmus paper turns red in an acid solution and red litmus paper turns blue in an alkaline (Base) solution. This is the first test used when experimenting with acids and bases. The litmus test tells you if your water solution is acidic, neutral or basic. Freshly distilled water is neutral with a pH of 7.0 and neither turns the litmus paper red or blue. Acids turn red with a pH of <7.0 to1.0. Bases turn blue and have a pH of >7.0 to 14. Some types of pH paper test strips can read pH with multiple color changes, indicating pH increments of 0.5 and 1.0.

  1. Specialized pH Paper for Correct Method application for Measuring Chemicals

    • Using the correct method for measuring pH for certain chemicals in industry and medicine requires a special pH range paper. For example, battery acid has a pH of 0 to 2.5. Alkaline water has a pH of 5 to 9. Urine/saliva has a pH of 5.5 to 8.0. Vinegar/yeast has a pH of 3 to 6. In these cases, an accurate pH reading can provide valuable information. The pH can indicate the product quality or the extent a chemical reaction has progressed within a process. It is a quality-control factor in the manufacture of chemicals and a measure of performance of some functions of the human body.

    Correctly Obtaining pH Measurements

    • Paper test strips have their limitations and interferences. They must be kept in sealed packets and out of direct sunlight. The shelf life is about two years. All solutions measured must be water based. You can not measure pH in oil. If you are checking pH for a soap- or oil-based product, wet the test strip first. Then immerse the strip into solution and withdraw. Wait a few seconds and take a reading, carefully measuring pH by comparing to the supplied color chart. If your solution is dark colored, it may distort your reading. Take several readings to check the test method's precision. Obtain a chemical similar to the one under test of known pH. Use it as a control to compare your unknown readings. Another method is to compare test strip readings to a calibrated pH meter.

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