For most of the following experiments, you will need a pH indicator, such as wide-range litmus or
a garden soil pH testing kit, or a pH indicator that you can make yourself in Experiment 3. These
indicators contain a chemical that changes color when it comes in contact with acids or bases.
litmus and pH paper turn red in strong acids and blue in strong bases. Because only a few pH
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
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
(paper)How to Measure with pH Paper
(soil)How to Measure Liquids with a Garden Soil pH Kit
(safe)Safety in the Laboratory
(observ)How to Record Observations
Experiment 1 --
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 --
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
After about two seconds, remove the paper, and immediately compare the color at the wet end of
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
liquids, such as water and water mixtures. Most of these kits contain a test solution (liquid pH
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
1/4 teaspoon of the test solution provided in the kit. Cover the container and shake once or twice
or stir if necessary. Compare with the color chart provided with the kit and write down the
- Except for wide-range pH test paper, all the materials called for in these experiments,
water and borax, can be obtained at grocery stores or from local lawn and garden stores or
- Wide-range pH test paper is inexpensive, but not easily obtained. A school science
probably have it or can order it, or you may order it through a biological supply company. Litmus
is usually included in chemical sets sold at toy stores for children over 8 years old.
- For the names of supply companies, you can consult the yellow pages of your
directory under a heading such as "Laboratory Equipment and Supplies." If your local directory
have such a heading, ask your teacher for suggestions or try the yellow pages from a larger city.
directories are available at many libraries.
- Inexpensive garden soil pH testing kits are available at most lawn and garden stores or
These testing kits usually contain a pH indicator solution that covers a range of at least pH 4 to
is wide enough for most of the following experiments.
- You may substitute baking soda for household ammonia in the experiments. If you do, be
sure to stir
well because baking soda does not dissolve easily in water unless heated. The pH of undissolved
soda will not be the same as dissolved baking soda.
- You may substitute fresh-squeezed lemon juice for white vinegar. Lemon juice is slightly
than the vinegar sold in grocery stores. White vinegar is preferred over cider vinegar or lemon
because it is colorless and relatively free of impurities.
- Use clean, dry containers and utensils.
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.
- Eye protection (goggles or safety glasses) must be worn when working on experiments.
Make a habit
of putting them on before the experiment begins and keeping them on until all clean-up is finished.
- Do not eat, drink, or smoke while in the laboratory.
- Do not taste any chemical.
- Long-sleeved shirts and leather-topped shoes must be worn at all times.
- Long hair must be tied back, so it will not fall into chemicals or flames.
- Do not work alone; work with an adult.
- Never perform any unauthorized experiment.
- All glassware must be washed and cleaned. Wipe all counter surfaces and hands with soap
- All experiments that produce or use chemicals that release poisonous, harmful, or
or vapors must be done in a well-ventilated area.
- Never point the open end of a test tube at yourself or another person.
- If you want to smell a substance, do not hold it directly to your nose. Instead, hold the
container a few
centimeters away and use your hand to fan vapors toward you.
- When diluting acids, always add the acid to the water; never water to acid. Add the acid
- Flush with large quantities of water when disposing of liquid chemicals or solutions in the
- If you spill any acid or base material on you, wash the exposed area with large amounts of
If skin becomes irritated, see a physician.
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.
- Use a bound notebook so that pages are not lost.
- Write complete sentences for all written entries.
- Use drawings as needed.
- Date each entry (even drawings).
- Use the title of the experiment as your first entry.
- When your observation entries have been completed, write your answers to the questions that
- Write your own thoughts about the experiment as the conclusion
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