Rocket Fuel

Description: Students will build rockets that are fueled with different propellants (vinegar and baking soda, lemon juice and baking soda, tap water and effervescent tablets, and seltzer water and effervescent tablets) and determine which one has the highest average speed (distance/time).

Learning Goals: Students will observe that neutralization of an acid with sodium bicarbonate yields gas

(carbon dioxide). Students will understand the basic chemistry behind gas-producing acid-base reactions. Students will use litmus paper to compare the pH of an acid and a base before and after

the two are combined. Students will test which acid-base combination results in the rocket with the highest

average speed. Students will learn to take measurements (mass, volume, and time) and analyze data.

Recommended Grades: K-8

Estimated Time Required:a) Prep Time: 10-15 minutesb) Class Time: 45-55 minutes

Key Concepts and Terms: The neutralization of acid with sodium bicarbonate yields carbon dioxide gas. Acid: a proton donor. Base: a proton acceptor. Neutralization: the name used to describe an acid-base reaction. An acid is

“neutralized” when its protons are accepted by a base. Conversely, a base is “neutralized” when it accepts a proton.

Proton: a particle with positive charge. Average speed: distance traveled divided by travel time. Sodium bicarbonate: baking soda; a base.

What Happens and Why: (How much detail to share is up to the teacher’s discretion): The vinegar and lemon juice are acids, while the baking soda is a base. The reaction

between baking soda (sodium bicarbonate) and vinegar (acetic acid) is shown below:

NaHCO3(s) + CH3COOH(l) → [H2CO3(aq) + NaCH3COO(aq)] → CO2(g) + H2O(l) + Na+(aq) + CH3COO-(aq).

Because carbonic acid (H2CO3) is unstable, it quickly decomposes into carbon dioxide (CO2) and water (H2O). The NaCH3COO breaks up into ions (Na+ and CH3COO-) in the solution.

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Effervescent tablets contain citric acid (C6H8O7) and sodium bicarbonate (NaHCO3), but they need to be in a liquid in order to react. When they are in a liquid (water or seltzer water), the following CO2-producing reaction, which is very similar to the one explained above, will occur:

3 NaHCO3(aq) + C6H8O7(aq) → 3 CO2(g) + 3 H2O(l) + 3 Na+(aq) + C6H5O73-(aq).

Seltzer water already has some CO2 in it (that is why it is fizzy). Therefore, it will be interesting to determine whether or not the CO2 already present in the seltzer water will increase the amount of CO2 to such a degree that the seltzer water/effervescent tablet propellant will cause the rocket to have a higher average speed compared to the rocket fueled by the tap water/effervescent tablet propellant.

Materials Needed: vinegar lemon juice baking soda tap water seltzer water effervescent tablets 1 empty 12 oz soda bottle 1 rubber band 1 small nitrile glove (or balloon, if there are no latex allergies) 8 coffee filters 8 film canisters 1 large plastic container stopwatches A-980 Alkacid Test Paper 8 oz measuring cup 1 tablespoon scale measuring tape graduated cylinder

Estimated Cost: $40-50 (can significantly reduce cost by eliminating the use of the scale—use volume measures instead—and the A-980 Alkacid Test Paper).

Safety Information: All of the chemicals used in this experiment are safe. Precautions will be necessary when launching the rockets. The children should stay within a safe distance, and the closing of the cap of the film canister should be done quickly to reduce the possibility of the rocket hitting the child.

Procedures:

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The teacher should do the following before class: Cut out and save the circle at the bottom of each coffee filter. This circle is the only part

of the coffee that will be used in the experiment. From now on, this circle will simply be referred as “coffee filter.”

Optional : Complete steps 1b-1c below.

1. Demonstration #1a) Challenge a student to blow up a glove (or balloon, if there are no latex allergies)

without touching it.b) Add 8 oz of vinegar to an empty 12 oz soda bottle. Then, add 1 tablespoon of baking

soda to a small nitrile glove (or balloon). Make sure to keep the baking soda as best contained as possible to facilitate the next step.

c) Use a rubber band to attach the glove to the top of the bottle very tightly. Be careful not to spill any baking soda onto the vinegar while you tie the glove to the bottle.

d) Place the bottle with the glove attached in a large plastic container and transfer all of the baking soda from the glove to the bottle as quick as possible.

e) The acid-base reaction will form carbon dioxide, which will blow up the glove. f) Pop the glove with scissors for a grand finale. Some excess baking soda will disperse

in the air.2. Explain the chemistry to the students (see “What Happens and Why” above). Use the A-

980 Alkacid Test Paper to compare the pH of the vinegar and a solution of 1 tablespoon of baking soda in 8 oz of water to the pH of what is left in the soda bottle after Demonstration #1. Mention that the same chemistry happens when you put an effervescent tablet in water.

3. Tell students that astronauts contacted you because they need new ways to launch rockets, and they want you to figure out what combinations of acid and base create the highest average speed. Define average speed.

4. Break up in the class into four groups. Each group will test out only one type propellant vinegar and baking soda, lemon juice and baking soda, tap water and effervescent tablets, or seltzer water and effervescent tablets.

5. Give each group two film canisters and two coffee filters. They need to add 20-22 ml (1.5 tablespoons) of the liquid portion of the propellant to the film canister. In the meantime, other members of the group can crush effervescent tablets (if applicable) and weigh out 1.45-1.55 g (1/4 teaspoon) of baking soda or effervescent tablet, using the coffee filter as a weigh boat. Instruct them to keep the liquid in the film canister and the powder in the coffee filter until it is time to mix them.

6. Set up a plastic container on the floor and place a film canister at the center. Measure the distance from the cap of the film canister and the ceiling of the classroom. This will be the total distance traveled by the rockets. With the recipe given, the rockets should travel at least 254 cm (100 in).

7. You will only be able to work closely with one group at a time. Give stopwatches to all the members of the group except for the student who will launch the rocket.

8. To launch the rocket:

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Tell the student to close the top of the coffee filter that contains the baking soda or crushed effervescent tablet as shown below:

a) Fold the paper into quarters, making sure that the contents remain in the center.

b) Place your thumb at the center and twist the top.

Then, tell the student to drop it into the film canister containing the assigned fluid and cap the film canister shut. The students should step back and the timekeepers should be instructed to start the time whenever they see the rocket take off and to stop the time whenever they see it hit the ceiling.

9. Record all of the times (see worksheets).10. Repeat steps 7-9 with the three remaining groups. Then, repeat again with all 4 groups.11. Average the data with the class to determine the average speed of the rocket with

different propellants. 12. Determine which propellant yielded the fastest rocket (highest average speed).

Special Notes: Closing the film canisters can be difficult for students, so you should give them some

time to get comfortable with the equipment. The students may also close their eyes when the rocket takes off, so it may be necessary

to make a few practice rockets so that they can get accustomed to the popping. Modifications For Different Ages: As written, the activity is suitable for 6-8th graders (see worksheet on page 6).

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For K-3rd graders, only use effervescent tablets dissolved in water and/or seltzer water. Only use enough water to cover the bottom of the film canister and ¼ to ½ of the tablet. This should give them enough time to close the film canister before the CO2 builds up. No need to collect data.

For 4-5th graders, use the activity as described above, but have the materials pre-weighed for them. Just use the fastest time in the class to decide which propellant yielded the fastest rocket.

Alternative Activity:Instead of testing different acid and base combinations, test different amounts of the same acid and base to determine if the proportion of acid to base affects the rocket’s average speed (see worksheet on page 8).

References:1. http://scienceline.ucsb.edu/getkey.php?key=41472. http://www.colorado.edu/MCEN/flowvis/galleries/2011/Team-3/Reports/

Scholbrock_Andrew.pdf

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Name: _________________________________________________ Date: _________________

Rocket Fuel Worksheet #1

Directions 1. Do not mix chemicals until instructed to do so.2. Using a coffee filter, weigh out 1.45-1.55 g of powder (baking soda or ground

effervescent tablet). I will show you how to fold the coffee filter when you are done. 3. A different team member should weight out another 1.45-1.55 g of powder.4. Measure out 20-22 ml of liquid (vinegar, lemon juice, regular water, or seltzer water)

and pour it into a film canister. Close the film canister.5. A different team member should measure out another 20-22 ml of liquid and pour it

into a different film canister. Close the film canister.6. Once there are two sets of liquids and powders measured, set up the plastic container

on the floor and place a film canister at the center. 7. I will show you how to launch the rocket.8. Before you launch your own rockets, do not forget that you have to know how long it

takes the rocket to hit the ceiling. Start the time whenever you see the rocket take off and stop the time whenever you see it hit the ceiling. Write the time down in the table below (“Travel time”).

9. Launch your rockets and record the data.

Data 1. Which fuel did you use? (circle one):

a) Lemon juice and baking soda

b) Vinegar and baking soda

c) Regular water and ground effervescent tablet

d) Seltzer water and ground effervescent tablet

2. Fill in the table below:

Trial Volume of vinegar (in ml)

Mass of baking soda (in g)

Distance traveled bythe rocket (in cm)

Travel time(in s)

1

2

3

4

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3. There are 2.54 centimeters in 1 inch. What is the distance traveled in centimeters?

4. What is the average distance traveled?

5. What is the average travel time?

6. What is the average speed of a rocket when it uses your fuel?

Average speed=average distance traveled (¿ cm)averagetravel time (¿ s)

=¿¿

7. Based on the average speed, which rocket fuel is the best?

8. Which measurement (mass, volume, or time) do you think is the least reliable? Why?

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Rocket Fuel Worksheet #2

Directions 1. Do not mix chemicals until instructed to do so.2. Using a coffee filter, weigh out the appropriate amount of baking soda. Write down

the exact weight in the table below (question #2). Ask an adult to fold the coffee filter for you when you are done.

3. A different team member should weight out a second portion of baking soda. Write down the exact weight in the table below.

4. Measure out 20 ml of vinegar and write down the exact volume in the table below.5. Pour the vinegar into a film canister. Close the film canister.6. A different team member should measure out a second 20 ml portion of vinegar and

write down the exact volume in the table below.7. Pour the vinegar into a different film canister. Close the film canister.8. Once there are two sets of vinegar and baking soda measured, set up the plastic

container on the floor and place a film canister at the center. 9. I will show you how to launch the rocket.10. The adults will time how long it takes the rocket to hit the ceiling. Start the time

whenever the rocket takes off and stop the time whenever it hits the ceiling. Write the time down in the table below (“Travel time”).

11. Launch your rockets and record the data.

Data 1. Which fuel did you use? (circle one):

a) 20 ml of vinegar and 0.5 g of baking soda

b) 20 ml of vinegar and 1.0 g of baking soda

c) 20 ml of vinegar and 1.5 g of baking soda

d) 20 ml of vinegar and 2.0 g of baking soda

2. Fill in the table below:

Trial Volume of vinegar (in ml)

Mass of baking soda (in g)

Distance traveled bythe rocket (in cm)

Travel time(in s)

1

2

3

4

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3. What is the average distance traveled?

4. What is the average travel time?

5. What is the average speed of a rocket when it uses your fuel?

Average speed=average distance traveled (¿ cm)average travel time (¿ s)

=¿¿

6. Based on the average speed, which rocket fuel is the best?

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