introduction to acids and bases what are they and how do we as scientists measure them?
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Introduction to Acids and Bases
What are they and how do we as scientists measure them?
pH Scale
1. The pH scale ranges from 0 to 14.
2. A solution with a pH of 7 is neutral.
3. Pure water has a pH of 7.
pH is a measure of how acidic or basic a solution
is.
Acids Bases
• Turns red litmus paper blue.
• Acidic solutions have pH values below 7
• Basic solutions have pH values above 7.
• Turns blue litmus paper red
Guess and CheckIn your notes, predict whether the objects below are acids or bases. What color will each turn the
litmus paper? Explain your reasoning.
1. Baking Soda and Water
2. Orange Juice
3. Vinegar
Three Ways to Measure pH
1. Liquid indicator
2. pH paper
3. pH meter
Pay Attention as I demonstrate how to use each of the three. You will need to know how to use each of these methods in the lab activity, which will count
as a grade.
Lab Activity• You will be assigned a group. You will be demonstrating
your knowledge on how to use the three pH measuring techniques.
• In your notes, begin by measuring the pH of water for each of the three techniques.
• Then measure the four other substances at your station.
• Create a data table to record your results. Remember to include three separate areas to record the data for each technique. o This will be collected and graded. If you fail to follow class expectations, you
will return to your seat and receive a zero!
Example Data TableSubstance Liquid
IndicatorpH Paper pH Meter Observations Acid or Base
Water
Lemon Juice
Bleach
Dishwasher Detergent
Soda
Stop and JotIn your lab notes, write 3-5 sentences to the following question. Be sure to explain your
answer clearly and support your answer with information learned from today’s lesson.
What method of measurement was the most accurate and which was the least?
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