“pH Lab”Lab Objectives: Test household substances in order to categorize them as acid/base or neautral.

HSA Question: Which pond is most acidic?

pH LabScientific Question:

•Is it an acid or a base?

You will create a hypothesis for several substances.

Keep a data table to record your hypothesis for each substance.

Create a table in your lab report with the following:

Substance Hypothesis/Prediction (use a number from pH scale)

Actual pH (after lab)

What was the difference between your prediction and the real pH?

Tap water

Vegetable juice

Coke

Baking soda (mixed with water)

Vinegar

Soap

Laundry detergent

4

ConclusionAfter you used your table to analyze

the data…

•Use a strip of paper to place the tested substances on a pH scale in the

appropriate place.

•For example… If saliva has a pH of 7 then it will be placed in the middle of

your pH scale.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

Data Analysis

• Put your data onto a graph.

• Where does the independent variable go on the graph?

• The dependent variable?

• Will you use a bar or line graph?

Maryland’s Water Samples Tomorrow!

• Extra credit on the lab if you bring your own water samples!

Water Sample Lab Day

• Hand in water samples if you have them!• Our lab rotation will depend on the number

of water samples.• Please start an open ended table with at

least:– 1. Pond Water– 2. Lake Water– 3. Chesapeake Bay Water– 4. River Water

Pre Lab1. What is the approximate pH of your stomach?

2. What happens when your stomach pH is out of whack?

3. A pond typically has a pH of 7. Recently, a chemical plant has been dumping their left overs into the pond. The pond’s pH has decreased to 5 on the pH scale.

A. Is this more acidic or more basic?

B. What effect will this have on the animals living in the pond?

C. What effect will this have on the enzymes living in the animals in the pond?

Sample Table (Leave Room at Bottom!)

Type of Water Sample

Predicted pH Actual pH

Pond

River

Chesapeake Bay

Lake

Open Ended! Leave Room!

Post LabData Analysis:•Explain the differences in pH for each of the water samples.•What was the most acidic water?•What was the most basic water?•Put your findings into a graph.

Conclusion:•Use your knowledge of marine environments to draw conclusions about the preferred pH for enzymes within each marine ecosystem that was tested today.