Acids and Bases Lab Activity: Standard 5c:
Purpose: Observe the pH of different household chemicals.
Background Information: Read pages 616-619 to answer the following questions below.
1. Many acids have what element? ______
2. When acids mix into water they separate into what 2 ions ______& ______.
3. What is a definition of an acid? An acid is ______
______.
4. Many bases are made if ______& ______.
5. What is a hydroxide ion? A hydroxide ion is ______
______.
6. What is a definition of a base? A base is ______
______.
7. Strong acids produce more ______than weak acids.
8. Strong bases produce more ______than weak bases.
9. Why are strong acids and strong bases dangerous?
10. What is used to describe the concentration of ions in a convenient way?
11. When the pH is low, the concentration of hydrogen ions is ______.
12. Substances with a pH lower than 7 is ______.
13. Substance with a pH higher than 7 is ______.
14. Substances with a pH of 7 is ______.
Procedure:
1)For each microtube, place a strip of blue litmus paper into it, so that a portion of it is in the liquid. Observe the changes and record the end color.
2)For each microtube, place a strip of red litmus paper into it, so that a portion of it is in the liquid. Observe the changes and record the end color.
3)For each microtube, place a strip of orange pH paper into it, so that a portion of it is in the liquid. Observe the changes and record the end color.
4)Identify if the chemical is an acid, base, or neutral. The pH range and color for the pH paper is shown on the container of pH paper. Remember:
Acids turn blue litmus paper ______.
Acids turnred litmus paper ______.
Bases turn blue litmus paper ______.
Bases turnredlitmus paper ______.
Data:
chemical / blue litmus-end color / red litmus-end color / pH paper-end color / acid, base, or neutral?antacid
baking soda
ammonia
lemon juice
lye
Milk of Magnesia
muriatic acid
fish tankwater
table salt
white vinegar
Questions and Assessment:
1)Some of these household substances have warning labels on their containers; which substances do you think they were. Why?
Going Further Part 1:
Your body naturally produces oils that secrete onto the surface of your skin. Oils dissolve best under basic conditions. As a result many detergents, soaps and shampoos are basic. Unfortunately, bases tend to dull and damage hair. For this reason manufacturers sell shampoo rinses. What do you predict the chemical nature to be of such rinses? Explain your answer.
Going Further Part 2:
You are an environmental scientist and have been asked to research a local waterway and stream to determine why the fish in the area are dying. In addition there seems to be a lack of vegetation growing in the location around the stream.
You notice that there is a large industrial plant located up stream and the company is a major producer of sulfuric acid.
You collect a sample of water and begin to test the pH of the water in three different locations, 1) at the end of the stream before it empties into a nearby lake, 2) a section of the stream two miles away from the lake, 3) a location that runs right by the industrial plant.
The following results are what you discovered:
Location 1 / Location 2 / Location 3pH / 6 / 4 / 2
Dead fish count / 4 / 7 / 27
1)Which location is the most acidic?
2)Draw a pH scale and label where each location would fall on the pH scale.
3) What can you conclude about the kind of chemical that the industrial plant is producing and is releasing into the stream?
4) What would be a way to neutralize the acidity of the stream?
5) Explain the differences between the properties of acids and bases.
6) Mr. Fix’s fish tank can no longer keep fish alive. Based on the results of the pH test (see data table), explain why fish die in Mr. Fix’s tank and explain what Mr. Fix can do to the water in the tank to make it livable for fish.