Body Chemistry Experiment:  Measure pH of Body

This is an easy experiment to learn about the chemistry of the body while you learn about pH.

The human body is made up of different elements.  All elements have different pH ranges.  Like elements, pH is measureable for the materials that make up the human body.  Not all people have the same pH.  In fact, each time you measure pH of body may vary by the day.  In this experiment, we will measure pH of the body by testing saliva.   **Follow all the manufacturer’s requirements for the pH test strips.  Do not place the pH test strips directly in the mouth.  If you are concerned about germs and have a fear that it may be too difficult to control kids performing the experiment, then this may not be the right experiment for your group**

Items Needed:

measure ph body

EXPERIMENT STEPS

  • Step 1

    Ask the person being tested to list the last items they ate or drank.  Record the list.

  • Step 2

    Have the person being tested carefully spit a small amount of saliva into the plastic cup.  Only a small amount is needed.  If you are concerned about germs either have each child perform the experiment on their own.  Otherwise, have the person testing wear non-latex disposable gloves.  In either case, have some hand sanitizer on hand for everyone to use after the experiment is complete.

  • Step 3

    Place the pH test strip into the test saliva for the amount of time listed in the test strip manufacturer’s instructions.  Some pH test strips will get a pH reading in 15 seconds, others require a few minutes for the test strip to change colors.

  • Step 4

    Compare the color of the test strip to the pH color key that came with the pH test strips.  Record the body pH value.  Compare this result with the list of items the person recently ate or drank.

SCIENCE LEARNED

From the measure pH body experiment, was the pH within a range of 7.  Doctors expect a person’s body pH to be in the range of 7.3 to 7.4.  The things that a person eats or drinks before the measurement, however, may skew the pH values.  pH is the abbreviation for power of hydrogen.  A pH of 7 is considered neutral.  A pH higher than 7 is a base (or alkaline). A pH less than 7 is an acid.  The human body is therefore slightly basic.  Acidic foods like citrus, vinegar, and soda pop (carbonic acid) which were recently consumed may lower the pH of the saliva test results.  If the person is sick or recently exercised, then the pH level may also be lower than the standard range.

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