What is the pH of some common household substances?
Problem: What is the pH of some common household substances? Are they acidic, alkaline (basic), or neutral?
Background Information: (READ THIS BUT DO NOT COPY IT IN YOUR LAB BOOK!) The pH scale is a numerical scale that goes from 0-14. Any number below 7 represents an acid. Any number above 7 represents a substance that is alkaline (base). The number 7 represents a neutral solution. The pH of a solution can be measured with special paper that changes color at different pH levels. Litmus paper can be used to identify an alkaline (basic), acidic, or neutral solution. Red litmus paper turns blue in the presence of a base. Blue litmus paper turns red in the presence of an acid. A neutral solution does not change the color of either red or blue litmus paper. Wide-range pH indicator paper can measure the actual pH of a substance.
Hypothesis/Prediction: (Write a statement that answers the problem above.)
I believe…
Materials:
paper
pencil
wide-range pH indicator paper and/or red and blue litmus paper
10 different solutions
plastic cups/beakers
paper plates
Procedure:
1) Record observations (appearance and smell) of the solutions in the table.
2) Predict the pH of each solution.
3) Test each solution with pH paper and record your results in the actual pH column.
4) Try to identify the substances in the appropriate column of the table. (If you are unsure leave it blank until your teacher assists you.)
5) State whether each solution is an acid, base or neutral.
6) Clean your work area. Be sure to dispose of materials properly. Wash your hands thoroughly before leaving your work area.
Results: (Copy this chart into your lab notebook)
Title (Create a descriptive title!)
# / Observation / Predicted pH / Actual pH / Substance / Acid, base or neutral?1
2
3
4
5
6
7
8
9
10
Conclusion/Analysis: (Write answers in complete sentences!!!)
1) Describe the pH scale.
2) Summarize your findings in two sentences. (How many solutions were acids, bases, neutral?)
3) Determine whether the predictions you made were correct. Explain any differences.
4) How could pH be an important factor in the environment?