Download Introduction to Acids and Bases

Introduction to
Acids and Bases
What are they and how do we as scientists
measure them?
pH Scale
pH is a measure of how acidic
or basic a solution is.
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.
Acids
Bases
• Basic solutions
have pH values
above 7.
• Turns blue litmus
paper red
• Turns red litmus
paper blue.
• Acidic solutions
have pH values
below 7
Guess and Check
In 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 Table
Substance
Water
Lemon Juice
Bleach
Dishwasher
Detergent
Soda
Liquid Indicator
pH Paper
pH Meter
Observations
Acid or Base
Stop and Jot
In 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?