Teachers Guide for Acid-Base Reactions
Many acids and bases can be found in your home. Acids
are things that usually taste sour and sting when they get
in your eye or a cut. Bases are things that usually feel
slippery or taste bitter. Do not taste things in a lab
because it could be dangerous.
Indicators can be used to test whether a substance is
an acid or a base. Indicators work by turning a certain
color in an acid or base. In acid an indicator will turn
red and in a base an indicator will turn blue. Litmus paper
is special paper that has an indicator on it so that it
will turn red or blue in acids or bases.
When acids and bases mix together, a neutralization
reaction occurs. After mixing an acid and base together the
new product is not acidic or basic, it is neutral. In a
neutralization reaction, a salt is formed.
The acid-base reactions activity is a fun way for
students to learn what household items are acidic and what
are basic. They will learn about indicators and special
paper with indicators on them called litmus paper. They
will the finally learn what happens when you add acids and
bases together to try and figure out what happened to a
wool sweater (acidic fiber) when it got bleached (base).
And how that is different from the cotton fabric (base) in
the bleach (base)
Materials (materials are enough for a group of 2-3
students)
14 containers or vials for holding liquids and solids
labeled with what they are (10 for the younger kids)
Lemon Juice
Cranberry Juice
Vinegar
Baking Soda (3 vials with powdered baking soda and 1 with
baking soda + water)
Detergent( 3 vials with powdered detergent and 1 with
detergent + water)
Windex
Egg Whites (older students only)
Astringent (older students only)
6 cups for mixing
Toothpicks for testing liquids
Litmus paper or cabbage juice (directions are written for
litmus paper)
Piece of wool fabric
Piece of Cotton Fabric
Chlorine bleach
2 Glass jars
Ahead of time place a piece of wool fabric in a glass
jar with bleach, cover and set aside. After about five
minutes, the fabric should begin to deteriorate because of
an acid base reaction. Also put a piece of white cotton
fabric in a jar of bleach and nothing should happen because
cotton is a basic fabric.
Story
“I just got a new wool sweater from my mom for my birthday,
and my sister was very jealous. It was this beautiful white
wool sweater. I had spilled some mustard on it one day so I
went down stairs to wash it with some bleach. I went
upstairs to wash the dishes and when I came back down my
new sweater was ruined. I think that when I was upstairs my
sister went down and ruined it. What do you think?”
or some version of the story.
Next introduce the activities by describing acids,
bases, indicators, litmus paper and for the older students
neutralization reaction. All of the key words are defined
on the student handouts.
You can explain to the students that there are
indicators that occur naturally like in red cabbages. You
can make an indicator by boiling red cabbage in water for
fifteen minutes and the juice can be used as an indicator.
If you put a few drop of cabbage indicator in a base the
solution will turn blue and if you put a few drops in an
acid it will turn red.
The students will then complete two activities. In the
first activity, they will test the liquids to see if they
are acidic or basic. The second activity, involves the
student mixing powdered baking soda and detergent with
acidic liquids (lemon juice, cranberry juice, vinegar, and
astringent) and then with basic liquids (Windex and egg
white). When mixed with acids, the detergent and baking
soda should fizz with a color change when mixed with
cranberry juice. When mixed with bases, nothing should
happen.
After completing the activity, ask the students if you
should test the bleach to see if it is an acid or a base.
The bleach is a base. Then tell them that you learned
cotton is a basic fiber or is a base and wool is an acidic
fiber or is an acid. Finally have them answer the rest of
the questions on the work sheet.
Mystery of the Wool Sweater
Acid-Base Reactions
Key words: acid, base, indicator
Many acids and bases can be found in your home.
Acids are things that usually taste sour and sting
when they get in your eye or a cut. Bases are
things that usually feel slippery or taste bitter.
Do not taste things in a lab because it could be
dangerous.
Indicators can be used to see if something is
an acid or a base. In an acid an indicator will
turn red and in a base an indicator will turn blue.
Directions:
Separate the containers that have liquids and
the containers that have powders. Put the powders
to the side.
Dip a toothpick into one of the liquids and
then onto the litmus paper. Does it turn red or
blue? If it’s red it is an acid. If it is blue it
is a base. Circle red or blue.
Lemon Juice
Red
Blue
Cranberry Juice
Red
Blue
Vinegar
Red
Blue
Baking Soda
Red
Blue
Detergent
Windex
Red
Red
Blue
Blue
When acids and bases mix together, reactions can
happen. Sometimes they fizz and make new things.
Sometimes they might change color.
Now using the powders, mix together the things
listed below in different cups and see what
happens? Do they fizz? Do they change color?
Baking Soda + Lemon Juice
What happened?
Baking Soda + Cranberry Juice
What happened?
Detergent + Vinegar
What happened?
Detergent +Windex
What happened?
Is the bleach red or blue?
RED
BLUE
Is the bleach an acid or a base?
ACID
BASE
What happened to the wool sweater?
Mystery of the Wool Sweater
Acid-Base Reactions
Key words: acid, base, indicator, litmus paper, neutralization reaction
Many acids and bases can be found in your home. Acids are things
that usually taste sour and sting when they get in your eye or a cut.
Bases are things that usually feel slippery or taste bitter. Do not
taste things in a lab because it could be dangerous.
Indicators can be used to test whether a substance is an acid or
a base. Indicators work by turning a certain color in an acid or base.
In acid an indicator will turn red and in a base an indicator will turn
blue. Litmus paper is special paper that has an indicator on it so that
it will turn red or blue in acids or bases.
When acids and bases mix together, a neutralization reaction
occurs. After mixing an acid and base together the new product is not
acidic or basic, it is neutral. In a neutralization reaction, a salt is
formed.
Directions:
Take out a piece of litmus paper. Using a toothpick dip it into
one of the liquids and then onto the litmus paper. Record what color it
turns and if it is an acid or a base. Put check marks in the
appropriate boxes. Continue to follow this procedure until each of the
liquids is tested. Record what each liquid is in the chart below and
then separate them into groups.
There are 6 vials with white powders in them. 3 of them are
baking soda and 3 of them are detergent. In 4 separate cups pour two of
the vials of detergent and two of the vials of baking soda. To each of
these cups add one of each of the liquids from the opposite group and
see what happens. Record your observations in the chart below.
Pour the remaining baking soda and detergent in two more cups.
Next pour in two liquids from the same group and see what happens.
Record your observations in the chart below.
Liquid
Paper
Paper
Acid
Base
Turns Red
Turns
Blue
Baking
Soda
Cranberry
Juice
Lemon
Juice
Egg Whites
Vinegar
Detergent
Windex
Astringent
Adding liquids from the opposite group (fill in what liquid you added)
Baking Soda + ____________________
What happened?
Baking Soda + ____________________
What happened?
Detergent + ____________________
What happened?
Detergent + ____________________
What happened?
Adding liquids from the same group (fill in what liquid you added)
Baking Soda + ____________________
What happened?
Detergent + ____________________
What happened?
Is the bleach acidic or basic? ____________________
What happened to the wool sweater?