Examples of pH ranges
Could my pH's be this low? How about this high?
WOW! I wonder why we're finding such low pH Values?
This graph is an excellent example of a hydrology site exhibiting low pH
readings. The question is how likely is it that pH's in my
water are really this low? This graph shows a
pH data range of about 3 to 4.5. Natural
waters tend to be in the pH range of 6 to 8?
Possibilities :
- This is real! If you think this is the case, then the next step is
to ask yourselves and your classmates why your water is so low. What does
this say about the path the water has followed to reach your Hydrology Study
Site?
- This is a product of how you did your tests. Unfortunately, although
we all try our best to make sure our data are accurate, sometimes there is
one step we missed which is causing an error in our data. Other times,
the materials we have to work with are not in good shape. In the case of
low pH values, it seems most likely that the solutions that the school is
using for calibration are no longer good. Certainly testing these standards
is a good place to start.
Testing your Standard Solutions
To investigate the possibility that your Standard Solutions are not good,
you have a couple of choices:
- Buy a new set of standard solutions and compare them to your old ones.
- Calibrate your pH meter with your solutions, then use it to test
the pH of a soft drink. These products, due to their production
standards, are very consistantly the same pH and can be used as a comparison
to see if your pH meters are measuring what they should be.
Below is a set of pH's for several soft drinks:
- Coca-Cola ........................2.5
- RC-cola ........................2.5
- Mr. Pibb .........................2.8
- Pepsi-Cola ...................2.5
- Sprite .............................3.2
- Barq's Rootbeer ...........4.0