Chemistry
of pH Lab
Objectives of this Lab:
• The student will be able to recognize an acid
and a base on the PH scale.
• The student will be able to read litmus and PH
paper.
2
Lab Materials Used:
• Common items –vinegar, hand sanitizer,
fizzing antacid tablets, apple juice,
baking soda, grapefruit juice,
• Red Litmus Paper
• Blue Litmus Paper
3
Procedures for this lab:
• Label your plastic cups #'s 1-6
• Choose one solution and pour a small amount into plas
tic cup #1.
• Write the name of the solution in your data table.
• Place a drop of the solution onto red and then blue lit
mus paper. Record results
• State whether each solution is an acid or a base.
4
Data:
Check One
Name of Substance
PH
Hypothesis
Red
to
Blue
Blue to
Red
5
Check One
No
Change
Acid
Base
Neutral
0-2 Most acidic lemon juice
3-4 apple, vinegar, tomato
5- banana
6- Milk
7-Neutral water
8- blood
8-9 baking soda
10-11 soap
11-12 ammonia
13-14 Most basic drain cleaner
6
How to Understand Litmus Paper
Red Litmus Paper Results
• Red paper turns blue (you are
working with a base)
• Red paper stays red
(not a base)
Blue Litmus Paper Results
• Blue paper turns red (you are
working with an acid)
• Blue paper stays blue (not an
acid)
*If there is no color change, then
you have a neutral substance.
7
Analysis Questions
1. Arrange the substances you tested on the pH scale by putting
them in order from 0 to 14.
2. When the pH of a substance is taken, what is actually being
done?
3. Stomach acid’s ph is between 2 and 3. Is this an acid or a base?
8
pH of Acids and Bases
• Use the internet or other resources to fi
nd the pH of each of the 6 substances.
• Record the pH of each substance in the
second column of your table.
9
How to write your conclusion
• First paragraph: restate the objectives, materi
als, and procedures used in this lab.
• Second paragraph: discuss the results from
the lab (mention all values on the data table).
• Third paragraph: Describe what the pH scale is
and what it is used for. Include as well the
common items on the scale.
• DUE NEXT CLASS NO EXCEPTIONS!
10