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For most of the following experiments, you will need a pH indicator, such as wide-range litmus or pH paper, a garden soil pH testing kit, or a pH indicator that you can make yourself in Experiment 3. These pH indicators contain a chemical that changes color when it comes in contact with acids or bases. For example, litmus and pH paper turn red in strong acids and blue in strong bases. Because only a few pH indicators measure pH over a wide range of pH values, you will need to find out the pH range of the indicator you use. Typically, the color chart provided with each pH indicator kit will show the pH range of that indicator. Color pH indicators provide only an approximate measure of the pH, or the strength of the acid or base. They are not as accurate as the expensive instruments scientists use to measure pH, but they are adequate for the following experiments.


(paper)How to Measure with pH Paper
(soil)How to Measure Liquids with a Garden Soil pH Kit
(tips)General Tips
(safe)Safety in the Laboratory
(observ)How to Record Observations


Experiment 1 -- Measuring pH:exp1
Experiment 2 -- Determining pH of Common Substances:exp2
Experiment 3 -- Making a Natural pH Indicator:exp3
Experiment 4 -- Measuring the pH of Natural Water:exp4
Experiment 5 -- Measuring Soil pH:exp5
Experiment 6 -- Soil Buffering:exp6
Experiment 7 -- Observing the Influence of Acid Rain on Plant Growth:exp7
Experiment 8 -- Observing Buffers in Lakes, Ponds, and Streams:exp8
Experiment 9 -- Looking at Acid Effects on Metals: exp9

Measuring With pH Paper

When measuring pH with pH paper, dip the end of a strip of pH paper into each mixture you want to test. After about two seconds, remove the paper, and immediately compare the color at the wet end of the paper with the color chart provided with that pH indicator. Write down the pH value and color. Always use a clean, unused strip of pH paper for each mixture that you test.

Measuring Liquids with a Garden Soil pH Test Kit

Soil pH test its are designed to measure the pH of soil, but they may also be used to measure the pH of liquids, such as water and water mixtures. Most of these kits contain a test solution (liquid pH indicator), color chart, and clear plastic test container, such as a test tube.

To measure pH, pour 1/4 teaspoon of the mixture you want to test into the test container, and add 1/4 teaspoon of the test solution provided in the kit. Cover the container and shake once or twice to mix, or stir if necessary. Compare with the color chart provided with the kit and write down the result.


Safety in the Laboratory

A science or chemistry laboratory can and should be a safe place to perform experiments. Accidents can be prevented if you think about what you are doing at all times, use good judgement, observe safety rules, and follow directions. Each experiment will include comments to alert you to probable hazards, including how to protect yourself and others against injury.

Recording Observations

Writing your observations on these experiments will help you to keep better track of the progress of the experiment. Written data are not forgotten. Record keeping can be very simple and still be a help. These hints can help you organize and record your thoughts.

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