“The Water Down Below” Procedure
Vocabulary:
 groundwater – water below the ground in a
water-saturated layer of soil or rock
 aquifer – any soil or rock formation that is






capable of supplying groundwater for
human use
contaminant – a substance that is poisoning
or polluting
pH – in chemistry, a measure of the acidity
or basicity of a liquid solution
quantitative – of or involving the
measurement of quantity
independent variable – factor that you wish
to test and that you change to identify its
effects
dependent variable – factor that you
measure to gather results
constants – all of the factors that must
remain unchanged in a scientific
investigation
Materials:










Eye goggles
Laptop loaded with Logger Pro software
Vernier pH probe
Ring stand
Clamp
One 10 mL graduated cylinder with medicine dropper
One 600-ml beaker containing 600 ml of gravel and 400 ml of tap water (Part I only)
One 1000-ml beaker used for waste
One 250-ml beaker of fresh water for rinsing the probe sample container
Contaminant obtained from teacher (Part I only)
Procedure Part I:
1.
Using the medicine dropper, remove 5 ml of water from the 600-ml beaker containing the
gravel and water.
2. Unscrew the pH probe sample container and pour in the 5 ml of water.
3. Replace sample container on probe.
4. Insert pH probe connector into a USB port of your laptop.
5. Open Logger Pro program on your laptop
6. In toolbar choose Experiment; then Data Collection from drop-down menu, or use
shortcut D; change mode to Events with Entry; Change both Name and Short Name to
Volume; Change Units to ml; click Done.
7. To begin collecting data, click green arrow on toolbar.
8. Enter data one of two ways: from the toolbar choose Experiment, then Keep from drop
down menu; or use shortcut K on the keyboard.
9. In the pop-up window enter 0 (for 0 ml contaminant) as your Volume value in ml; click OK.
10. Your data will be automatically entered in the data table to the left of the graph, and your
data points will automatically be added to your graph.
“The Water Down Below” Continued
11. Unscrew the pH probe sample container and empty the contents into the 1000-ml waste
beaker.
12. Add 1 ml of contaminant to the 600-ml beaker containing the gravel and water. Wait one
minute to allow contaminant to mix into the water.
13. Using the medicine dropper, remove 5 ml of contaminated water from the 600-ml beaker
containing the gravel and water and pour this into the pH probe sample container.
14. Replace sample container on probe.
15. Enter data into the program using Step 8. In the pop-up window enter 1 (for 1 ml
contaminant) as your Volume value in ml; click OK.
16. Unscrew the pH probe sample container and empty the contents into the 1000-ml waste
beaker.
17. Rinse the pH probe sample container with fresh water before your next trial.
18. Repeat steps 12 through 17 two more times, each time adding 1 ml of contaminant to the
600-ml beaker with the gravel and water. Enter 2, and then 3 as your Volume value in ml;
click OK.
19. To stop data collection, click on the red button on the toolbar.
20. After analyzing your results (data table and graph), complete the following relational
statement.
The __________ the concentration of contaminant, the ___________ the pH.
greater or less
higher or lower
I can say this because _________________________________________________
__________________________________________________________________.
Part II “Where’s the Leak?”
Scenario:
Some residents in the town of New Evanston have noticed that their drinking water is
beginning to taste and smell bad. Town officials order tests on the well where the town’s
drinking water comes from. The groundwater inside the well has a pH 2.45.
The residents of the town remember from science class that pollution can contaminate
groundwater. But where is the pollution coming from? A landfill, a water treatment plant, and
a coalmine surround the town. Any of these could be a source of contaminants. The managers
of each facility insist that they have passed all of their health and safety inspections and could
not possibly be leaking contaminants into the ground.
The town of New Evanston hires you as an expert scientist to identify which facility is
contaminating the groundwater. First you must decide how you will investigate this problem.
You only have enough resources (time, money, and employees) to collect and test
approximately ____ samples. Where would you like to collect samples? Look at the map of New
Evanston. Write your hypothesis.
Procedure
1. In toolbar select Experiment; then Clear Latest Run.
2. With your teammates, look at the map of New Evanston; decide which ____ sites will be
tested and which one you will be responsible for. Record that sample # ____.
3. Obtain the sample from the team leader and return to your testing station.
4. Test your sample by placing 5 ml of the sample into the pH probe sample container.
“The Water Down Below” Continued
5. Obtain the pH reading from the computer and write it on your New Evanston map next to
the number corresponding to your sample number. Report this number to the team leader.
6. Be sure to rinse the sample container when you are finished.
7. Record the pH values obtained by your teammates.
8. After analyzing the results, decide where the source of the contamination is.
Constants: Identify some constants in this investigation.
_____________ _____________ _____________ _____________ _____________
Independent variable: proximity of collected sample to the contamination source
Dependant variable: pH level
Investigation Question: Will water samples collected close to a contamination source have
a different pH than water samples collected further from the contamination source?
Hypothesis: (before investigation) If a water sample is collected close to the contamination
source, then the pH level will change, because __________________________________
______________________________________________________________________.
Claim: (during/after investigation)
*My hypothesis is/is not _________________
supported. ***I can say this because _______
____________________________________
____________________________________
____________________________________
Evidence: ** (chosen from your data)
1. ______________________________
2. ______________________________
3. ______________________________
Explanation: (Make clear connections between claims and evidence; how does your
evidence support your claim?)
Example template:
*My investigation showed that my hypothesis …
**The evidence that supports this is ... I think this evidence supports my claim because…
***I think this all happened because…
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________
_____________________________________________________________________