Watching a spacecraft launch is an amazing experience. It is thrilling to see it lift off and escape Earth’s gravity. Did you know that it takes a chemical reaction to get a spacecraft into space? Every time you see a one blast off, you are watching chemistry at work. In this chemistry science fair project, you will also get to blast an object into the air. You will not be using the same fuel that NASA uses for the rockets that launch their spacecrafts; instead, you will use two simple ingredients—baking soda and vinegar. How much do you need of each to get the highest launch height?
To determine the correct ratio of baking soda to vinegar that will result in the highest launch of a plastic canister.
Have you ever watched a spacecraft launch on television or seen one live? One question that may have crossed your mind when watching this awesome spectacle is, “How does a spacecraft lift off and get into space?” The simple answer to this question is that the spacecraft has engines that lift it into space. All rockets depend on combustion to provide the thrust that is required for a vessel to overcome the force of gravity and climb into space.
One well-known spacecraft that you may have seen launch is the National Aeronautics and Space Administration (NASA)’s Space Shuttle, shown in Figure 1 below. The Space Shuttle did operational flights for 30 years, from 1981 to 2011. It had three major components: the orbiter (a winged “space-plane” which held the astronauts and different kinds of payload), the large, dark orange-colored external fuel tank, and two solid rocket boosters. At launch, the two solid rocket boosters, along with the orbiter’s three main engines, would power the liftoff.
Figure 1. Rocket engines on spacecrafts, like NASA’s Space Shuttle (shown here), use a type of chemical reaction called combustion to launch the spacecraft. On the right in this picture you can see the Space Shuttle and its three main components: the orbiter (the white winged plane in the middle), the large external fuel tank (behind the orbiter), and two solid rocket boosters (also behind the orbiter, on the left and right sides).
Contrary to popular belief, it does not take an explosion to get a spacecraft off of the earth. Rocket engines function on the principle of combustion. Combustion is a fast chemical reaction between a fuel and an oxidizer (such as oxygen) where the fuel is burned or oxidized. Usually the fuel is an organic compound (containing hydrogen and/or carbon, and sometimes even metals). For example, on the Space Shuttle the orbiter’s three main engines used liquid hydrogen as the fuel and liquid oxygen as the oxidizer. However, the Space Shuttle’s two solid rocket boosters used aluminum powder as the fuel and ammonium perchlorate as the oxidizer.
During combustion, new compounds are made and these are called the exhaust. At the same time, a great amount of heat is produced because combustion is an exothermic reaction (it makes energy, in the form of heat and/or light). Altogether, the combustion in the spacecraft’s rockets produces great amounts of exhaust gas at high temperatures and pressure. The pressurized hot gases are pushed out from the bottom of the rocket and thus, the spacecraft is thrust upward. This is an example of Isaac Newton’s third law of motion, which states that for every action, there is an equal and opposite reaction.
Mixing the fuel and oxidizer together correctly is complicated and something that real rocket scientists work hard to perfect. In this chemistry science fair project, you will become a rocket scientist, but instead of using rocket fuel and oxidizers, you will use baking soda (sodium bicarbonate, or NaHCO3) and vinegar (acetic acid, or CH3COOH) to make a different kind of chemical reaction that can launch a small-scale rocket. This reaction is shown in Equation 1 below. Based on acid/base chemistry, the reaction produces water (H2O) and carbon dioxide (CO2). (You do not need to know acid/base chemistry to do this science project, but if you want to learn more about it, you can check out the Science Buddies resource Acids, Bases, & the pH Scale.) Carbon dioxide is what makes soda fizzy and bubbly, which is why you see lots of bubbling and foaming when you mix baking soda and vinegar together. You will mix baking soda and vinegar in a capped film canister and take advantage of the pressure the carbon dioxide gas creates in the canister to launch your own small-scale rocket. When the pressure (or force being exerted against the inside of the canister by the carbon dioxide gas) is great enough, the canister’s lid will pop open and the rocket will launch. How will different amounts of baking soda and vinegar affect the launch height? While trying to answer this question you might not be launching the Space Shuttle, but you will still have messy fun escaping the force of gravity for a few seconds with your own rocket!
Terms and Concepts
- Chemical reaction
- Oxidizers or oxidants
- Newton’s third law of motion
Materials and Equipment
- Plastic film canister with a lid and tight seal. Fuji® or Kodak® should work well.
- Optional: Construction paper, any color (1 sheet); transparent tape; and scissors.
- Masking tape or painter’s tape. Painter’s tape can be purchased at most hardware stores or online
- Outdoor space next to a tall exterior wall, with nothing above it, where tape can be applied with permission. It is ideal to have a hard, flat surface, like a paved patio or driveway.
- Permanent marker
- Metric ruler, tape measure, or meter stick
- Optional: Ladder
- Baking soda (1 fresh, unopened box)
- White vinegar (1/2 gallon bottle or jug)
- Measuring spoon, 1/8 tsp.
- Measuring spoon, 1 tsp.
- Safety goggles
- Adult volunteer, adult volunteer with a video camera, or a video camera with a tripod
- Lab notebook
Preparing Your Test Area
- If you want, you may decorate your film canister, which will be the body of your rocket.
- You could take a piece of construction paper and wrap it around the film canister. Make sure to wrap along the short side of the paper, about 2 millimeters below the lip of the canister, and make sure that the lid is not enclosed or covered by the tube of paper. Wrap the paper neatly and evenly along the canister and use the scissors to remove the excess paper from the bottom. Secure the paper with a few pieces of transparent tape.
- Make sure it is still easy to put the lid on the canister.
- Now go outside to your test site, which should be an open area next to a tall exterior wall, with nothing above it. Prepare the test site so you will be able to measure how high the rocket goes.
- Put a long piece of masking tape or painter’s tape on the wall, just 15 centimeters (cm) from the ground. The piece of tape should be about 50 cm long.
- Then put a long piece of tape every 15 cm up after that until you reach the top of the wall (or about 4 meters [m] high). Ask an adult to help put up the higher pieces of tape (possibly using a ladder may be needed).
- Use the permanent marker to label each piece of tape. For example, the first piece should be labeled “15 cm,” the next should be “30 cm,” and so on.
- Create a data table in your lab notebook so that you can keep track of the data that you collect. It should look like Table 1 below.
|Amount of Baking Soda
|Amount of Vinegar
|Average Launch Height
Table 1. In your lab notebook, create a data table like this one to record your data.
Preparing the Rocket
- Now prepare the baking soda for the rocket.
- Place 1 teaspoon (tsp.) of baking soda in the bowl. Carefully add 1/8 tsp. of water to the baking soda and mix it in using the spoon. This should wet the baking soda enough so that you can pack it into the depression on the inside of the canister lid.
- Turn the film canister lid over and tightly pack the inside of the depression with the damp baking soda, as shown in Figure 2 below.
- Briefly turn the lid upside-down and make sure that the baking soda does not fall out. If the baking soda all falls out, then add a little bit more water to the baking soda and mix it in. Try to add only a minimal amount of water to the baking soda in order to make it stick together inside the lid.
- Record the amount of baking soda that you used in the data table in your lab notebook.
Figure 2. Tightly pack the damp baking soda in the depression in the lid. Try not to let the baking side go outside of the depression or it make be difficult to snap the lid on the canister.
- Now prepare the vinegar for the rocket.
- Add 1 tsp. of vinegar to the canister at a time, filling it almost to the top. You need to add as much vinegar to the canister as possible without the vinegar and the baking soda coming into contact when you eventually snap the lid onto the canister, as shown in Figure 3 below. (Tip: Depending on the exact canister, this may be around 5 tsp. of vinegar.) This might take a little trial and error, but be patient and keep trying.
- Keep careful track of and record the amount of vinegar in the data table in your lab notebook.
Figure 3. Fill the film canister with as much vinegar as you can (1 tsp. at a time) without it coming into contact with the baking soda when the lid is put on the canister. (Tip: This may be around 5 tsp. of vinegar.)
- Go over to the outdoor area where you put tape strips on the wall and prepare to have your experiments videotaped or watched by a volunteer.
- If you want to videotape your experiments, use a tripod or an adult volunteer to set up the video camera so that it has in its viewfinder the spot where you will launch your canister rocket and the tape strips on the wall. Have the camera start recording at the beginning of step 4, and stop recording at the end of step 6.
- If you do not have a video camera, you can alternatively ask a volunteer to watch the reactions to help you figure out how high the canisters go.
- Launch your rocket.
- Put on your safety goggles. Stoop down near the ground on a flat, hard spot and quickly snap the lid onto the canister to seal it. Immediately turn the canister over so the lid is on the ground, and quickly move away.
- Wait for the chemical reaction to occur (the time depends on the amount of baking soda and vinegar you are using).
- When the lid finally pops off, the rocket should overcome gravity and launch. You and your volunteer should watch to see how high it goes and record the launch height in the data table in your lab notebook.
- Carefully rinse out the lid and canister with water.
- If your canister is decorated, make sure that the construction paper does not get too wet.
- Repeat steps 1–5 two more times, always recording the launch height in the data table in your lab notebook.
- It is a good idea to perform at least three trials of each experiment so that you know your results are accurate and reproducible.
- Decrease the amount of vinegar in the canister by 1 tsp. and repeat steps 1–6. Record all of the data in the data table in your lab notebook.
- Once again, reduce the amount of vinegar by 1 more tsp. and repeat steps 1–6. Always record all of the data in your lab notebook.
- Now that you have investigated the effect of the amount of vinegar on launch height, investigate how the amount of baking soda affects the launch height.
- Reduce the amount of baking soda to ½ tsp. and repeat steps 1–6, with the original amount of vinegar used for your first vinegar trial. Adjust and use just enough water for the baking soda to stick to the depression in the lid. Record all of your data in the data table in your lab notebook.
- Repeat step 9a but this time reduce the amount of baking soda to ¼ tsp.
Analyzing the Data
- Average the launch height data for each set of trials that you recorded in your data table. (The amount of baking soda and vinegar used in a set of trials should be the same between the different trials.) Write the averages in the far right column of your data table.
- Using the averages data in your data table, make two line graphs. One graph should have the average launch height for when the amount of baking soda stayed the same (all 1 tsp.) but you changed the amount of vinegar. The second graph should have the average launch height for when you kept the amount of vinegar the same but changed the amount of baking soda.
- You can make your plots by hand on graph paper, or if you would like to make your plots online, try the following website: Create a Graph.
- For one graph, label the x-axis “Amount of Vinegar (tsp.).” For the other graph, label the x-axis “Amount of Baking Soda (tsp.).”
- For both graphs label the y-axis “Average Launch Height (cm).”
- Plot the average launch height for the varying amounts of vinegar or baking soda on each graph.
- Analyze your graphs and try to explain your results.
- Based on your results, what is the ideal amount of baking soda and vinegar to use?
- Which variable affects the launch height the most, vinegar or baking soda?
- Do you see any trends in your data? If so, can you explain them? Do your trends correlate with other observations you made, such as whether it took a longer or shorter amount of time for a rocket to launch? Hint: You may want to re-read the Introduction in the Background tab and think about how pressure (from carbon dioxide gas) played a role in causing your rockets to launch.
- Do you think that adding a cone and fins to your rocket will help it have a greater launch height? Add a cone and see how that affects the launch height using the amount of baking soda and vinegar that previously produced the highest launch. Then design and make fins for your rocket out of construction paper and repeat the experiment using the amount of baking soda and vinegar that previously produced the highest launch. Tape the cone on the opposite end from the canister and the fins on the same end. Do the cone and fins help increase the launch height?
- Try using different containers instead of Fuji or Kodak film canisters. Are there other types of containers that work well for making a small-scale rocket?