Materials:

Plastic film canister

Alka Seltzer Tablets

Mortar and Pestle

Vinegar

Baking Soda

Hot Water

Ice Cubes

Water

Small white boards

Dry erase markers

Introduction: Students will investigate kinetics by identifying the factors that influence the rate of a chemical reaction and testing one or more factors in a self-designed experiment. The teacher will demonstrate the launch of an “alka seltzer rocket”. Afterwards, students will be asked to come up with a list of factors that influenced both the speed and height of the rocket launch. Students will then test one or more factors to determine which have the greatest effect on reaction rate. The reaction we will be studying is the production of CO₂ from alka seltzer in water:             3NaHCO_3(aq) + H₃C₆H₅O_7(aq) ® 3H₂O + 3CO_2(g) + Na₃C₆H₅O_7(aq) 

Prior Knowledge: Students should be familiar with gas laws and kinetic molecular theory. They should remember the effects of temperature, pressure, and volume on the production of carbon dioxide in a closed system.

Procedure:

Part 1:Teacher Demonstration (20 minutes)

Note: Students and all materials should be taken outside to a safe and quiet area, away from other students. Alka rockets CANNOT be shot off indoors! Students should bring safety goggles and wear them throughout the rocket launch. 

1. Add a few milliliters of water to film canister. One Alka Seltzer tablet should be gently placed on the rim of the canister. Quickly place the lid onto canister and invert, placing it on the ground.

2. Alka rocket should launch into the air. Get ready for a second launch. This launch will act as a control for the students’ experiment. During the second launch, have students record the amount of water in canister, the time it takes for launch as well as estimated height of launch based on a scale such as the one below:

1 – Grounded

2 – We have lift off!

3- Apollo 13 – on its way but didn’t quite make it

4- Worthy of a moon bounce

5- Out of this world!

3. Break students into small groups and allow each group three white boards and dry erase markers. Ask students to come up with a hypothesis on how to make the rocket launch faster and/or higher. Before students begin discussion, provide them with a list of available materials for experimentation.

Part 2:Experimental Design (30 minutes)

1. Students should write down their names and hypothesis on one white board. This white board can be handed in to teacher.

2. Students will write a procedure for an experiment to test their hypothesis. Their procedure should be approved by the teacher before they are allowed to begin experimentation.

[Some possible student experiments may include: using hot/cold water, using vinegar rather than water, crushing the tablet, using more/less tablets, etc.]

Part 3:Experimentation and Conclusions (40 minutes)

1. Students will perform their experiment and record results including the time of launch and the height of launch.  Results should be recorded both in notebook and on a 2^nd white board for easy presentation to the class

2. Each group should share their hypothesis and results.

3. Students will clean up outdoor area and bring all materials inside.

4. Once inside, class discussion will begin. As a class, students will record all of the factors tested and the results in a chart:

5. Students will come up with many factors that influence the rate of a reaction including temperature, surface area, concentration, and nature of reactants. Students will most likely not come up with a catalyst as a factor and the teacher will need to provide information.

                 6. Exit Card Assessment – ask students to draw or write one thing they learned during their experiment and how it relates to the speed of a chemical reaction.

Part 4:                 Experimental Analysis (Done at home)

Students will complete a full lab write up which includes their hypothesis, materials, procedure, class data, and a conclusion. Students should include the following in their data & analysis section:

1. What factors had the greatest effect on the launch of the rocket? Justify your answer.

2. Describe the mechanism by which a chemical reaction occurs. What is required for a reaction to happen?

3. Explain how the kinetic molecular theory correlates to the factors that affect the rate of a chemical reaction. 

4. What connections can you make between kinetics and gas laws? Can these be true for other phases of matter? Why or why not?

5. How could you quantitatively measure the rate of the chemical reaction?

6. Suggest further experimentation based on what you learned in class. Assume you have unlimited materials.

Assessment: Students will be assessed on participation in experimentation, design of experiment and final lab write up. The next day, a short quiz will be given in class to test knowledge of the factors that affect reaction rate.

National Science Education Standards Grades 9 to 12