pH Testing

Student procedure guide - Global Lab

Why We Care

Corrosion of metal can cause a change of pH of the water; conversely, change in pH might increase or slow corrosion of metal. These changes may cause certain substances to become toxic to fish and other living beings, so pH is a water quality important to monitor.

Materials

protective goggles
gloves
clean, clear high-density polyethylene (HDPE -#2 plastic) or glass jar
TERC water pump
pH strip
color chart
water samples taken from several different locations

Procedure for Testing for pH

1 Put on protective goggles and gloves.
2 Collect a water sample into a clean, clear high-density polyethylene (HDPE - #2 plastic) or glass jar, using either the TERC water pump (for samples from depth) or the sample collection method described in for surface samples.
3 Dip a pH strip into the sample for 10 seconds.
4 Wait 30 seconds for the color to develop.
5 Compare the colors on the strip with those on the color chart. Read the pH of the sample.
6 Repeat with several water samples taken from different locations.

Possible Investigations:

• You can explore the pH of different liquid substances.
• You can explore the variation of the pH of a liquid as it changes temperature.
• You can measure the pH of different concentrations of salt solutions.
• You may look at how changes in pH may possibly change other factors in the water (or how other factors affect the pH level), and see if those same factors also cause a change in conductivity.
• You can hatch brine shrimp in a gradient of different pH levels, to see the effects of pH on the rate of hatching eggs.

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