DISCUSS:
This probably isn’t the first time you’ve heard the word "acid." What does this word make you think of?
I don't have a Mystery Pack
In your Mystery Pack Lesson Bag
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|
---|---|
Acid Test Results printout | 1 per student |
Acid Test Results Answer Key printout | 1 per class |
Mixing Sheet printout | 1 per pair |
Testing & Acid Reaction Supply Mats printout | 1 per group |
1 Acid (Mustard) | 1 pack per group |
Baking Powder | 1 tablespoon per group |
Beans (Dried, Black) | 7 ounces per class |
Coffee Stirrers
Cut stirrers from your Mystery Pack in half before distribution |
4 sticks per group |
Cups (Dixie 3 oz) | 7 cups per group |
Plastic Straws (Not Bendable) | 5 straws per 8 students |
Toothpicks | 2 toothpicks per pair |
In your Mystery Pack Shared Supplies
|
|
Baking Soda | 1 tablespoon per group |
Measuring Cup | 1 cup per class |
Measuring Spoons | 1 set per class |
Plastic Bin
Used to make your indicator liquid. |
1 bin per class |
Salt | 1 cup per class |
Sheet Protector | 1 per pair |
White Vinegar | 2 tablespoons per group |
Not included in your Mystery Pack
|
|
Acid Test Results printout | 1 per student |
Acid Test Results Answer Key printout | 1 per class |
Mixing Sheet printout | 1 per pair |
Testing & Acid Reaction Supply Mats printout | 1 per group |
Clean-up Supplies (Eg. Paper Towels)
In case of spills. |
1 roll per class |
Table Covering (eg. Trash Bags) | 2 bags per group |
You will need access to water for this activity.
We suggest students work in pairs and two pairs of students share supplies at the same table group.
Put 1 cup of black beans into 2 cups of water and leave them for at least an hour. The beans will soak up some water and turn the rest purplish brown. Drain the beans and reserve the purplish-brown liquid.
Cut each straw in half to make two short straws. Students will use these to transfer drops of liquid. (Full-length straws are likely to tip over cups.)
Gather all of your Dixie cups and separate them into seven equal piles. You will fill the cups in each of these piles with a different liquid or powder.
We recommend you set up four supply stations.
Station A: Acid Reaction Supplies
From this station, each group of students will bring the following back to their desk:
Station B: Testing Supplies
From this station, each group of students will bring the following back to their desk:
Station C: Worksheets & Clean-up Supplies
From this station, each pair of students will bring the following back to their desk:
Station D: Substances
From this station, each pair of students will bring the following back to their desk:
The purple liquid that you prepare from the black beans is called an indicator. There’s a pigment in black beans that changes color when it reacts with an acid or base. You and your students should notice that the color of the liquid changes to a reddish/pink when you add it to any of the acids (e.g. vinegar). You can then use this information to test unknown liquids. If the liquid turns pink, then it’s an acid.
You and your students will also notice that when baking soda is mixed with vinegar, there is fizzing that indicates an acid-base reaction. But baking soda does not fizz when mixed with water, making it a good acid indicator. Baking powder will also fizz with vinegar. But you will notice that baking powder will also slightly fizz when water is added. This is because baking powder is actually a mixture of baking soda (base) and cream of tartar (acid). This is why it reacts with both water and vinegar. So baking powder is not a good indicator because it fizzes when any liquid is added.
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