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Lesson Idea from:

FOSS (Full Option Science System) Mixtures and Solutions, Investigation 4: Fizz Quiz (p. 22)

Purpose: To allow students to gain hands on experience with chemical reactions and the amount of gas produced in a closed system. Students will witness how a reactant is produced and will be capable of evaluating and synthesizing information attained. TEKS §112.7 (a) (b) (1) (2) (3) (4) (7).

Materials for the teacher:

1 Large zip bag 1 small zip bag

One can of soda

 Materials per group:

2 Small zip bags

1 Syringe Calcium Chloride

1 Container of water Baking-Soda

Safety goggles Citric-Acid

5 ml spoon Little Scientist Journal hand out

Hook: Take a soda can and furiously shake it. Put inside the large zip bag and seal it. Allow students to see what happens when you open the can inside the zip bag.

 Preliminary Discussion: Permit students to ascertain why the can exploded. Ask students what their concept of chemistry is. Then ask if they believe that the process that took place in the can while being shaken had anything to do with chemistry.

 Procedure:

• Place students in groups of three. Each group should have all the materials
• The student will get one leveled spoon of calcium chloride and one leveled spoon of baking soda and drop into the small zip bag.
• The student will then zip the bag closed leaving an opening about the size of the syringe. (The student should push all the air out of the bag in the process
• The student will get 50 ml of water with the syringe and quickly add it to the zip bag and close it.
• All students observe as the group members take turns holding and gently shaking the bag.

Pedagogical Method:

• Now the student will conduct the same experiment as in steps 2-5 utilizing citric-acid and baking soda.

• Now the teacher will demonstrate adding one level spoon of all three of the materials into a zip bag: calcium-chloride, baking-soda, & citric-acid.

Ask students how they think the bag will react now.

Assessment:

 This activity should continuously be assessed in order to allow students to make corrections and learn from them. Then a final assessment should be conducted at the end of the lesson inspecting whether the chemicals reacted correctly.

 Discussion:

• Introduce the concept of a reactant. Reactants are two chemicals that when put together form a reaction. In order to retrieve background knowledge, talk about what happened with the can that was shook. When furiously mixing the carbonated water, corn syrup, citric acid, sodium citrate and sodium benzoate in the can, it produces a gas that creates an explosion upon releasing the tension.

• Ask students who we know that a gas was formed in the experiment. Discuss the idea that gas in tangible in the form of bubbles yet breaks free of the liquid and disperses into the air.

• Discuss how it was possible to determine which reactant produced more gas.

• Finally, ask the initial question whether the process that too place in the can had anything to do with chemistry and why.
  

By having students make the connection that chemistry is all around us and that we are exposed to it on a daily basis will prompt awareness and will allow students to later build upon the knowledge obtained.

For printable version of the "Little Scientist Journal" |click here|

See what the zip bag may look like |click here|

For more information e-mail me at:
mnlozano28@yahoo.com