Bubbles and heat

Energy can be generated in so many ways. Try this energy experiment to explore a chemical reaction.

This experiment uses materials you can find around the house. You will mix two substances to make a third. Heat will be a factor as chemical energy. What do you think will happen when you make the mixture?

Safety note: Be sure to explain safety precautions to children. This experiment uses acids and bases. Eye protection should be used. Measuring devices should not be mixed between substances. Disclaimer: All information provided on this site is for entertainment purposes only. Using any information from thecasabouquet.com is at your own risk.

Instructions

Power on the Vernier LabQuest. Press the “home” key and select LabApp. Connect the temperature probe in CH1 at the top of the LabQuest. Use the probe to collect temperature data. Note: this experiment can be done with a thermometer. It can also be done qualitatively by using your hand outside the bag to feel the temperature and note the differences.

Record the room temperature first. Measure 1 tsp of vinegar with the teaspoon measure. Pour into an empty plastic bag. Measure and record the temperature of the vinegar in the bag. Feel the outside of the bag with your hand and record your observations.

Scoop 1 tsp of baking soda with the assigned teaspoon. Carefully pour into bag.

Quickly, put the temperature probe in the bag and record the temperature again.

Remove temperature probe from the bag, and feel the outside of bag. Note temperature change.

When done, carefully seal up the plastic bag and dispose in the trash.

You can continue exploring if you have some litmus or hydrion pH paper or make some red cabbage indicator. Test the pH of the baking soda, the vinegar, and the product solution. What happens to the pH of the product if you double the vinegar? Double the baking soda? Would the product solution of this reaction make a good cleaner around the house?

Supplies

• vinegar,
• baking soda,
• reclosable plastic bags,
• paper towels,
• Paper or notebook for recording results, pen
• LabQuest, temperature probe,
• blue scoops (or two 1 tsp measures, or two small medicine cups).

Label the scoops with “vinegar” and “baking soda”. You donʻt want the “vinegar” spoon in the baking soda container! If you are doing this with large groups of children, the blue scoops are great. Plastic medicine cups work, but it’s hard to see the markings. You can use a permanent marker on the outside to make the marks more visible.

I recommend getting vinegar in a plastic bottle and using a reclosable plastic bag to store the box of baking soda. Keep the original containers as your “stock” containers and give the children the materials in smaller labeled containers to help with cross-contamination.

I’ve found that inexpensive classroom thermometers (the kind with the red alcohol inside) don’t hold up well if used with lots of children. A cooking thermometer will work.

Small cafeteria trays are great for containing mess. They help if you have to set up several workstations. They are also handy for encouraging children to help in the clean up process.

What is the science?

Content: energy, thermodynamics, endothermic, chemical reaction, temperature

This experiment involves mixing vinegar and baking soda together and measuring the temperature difference of the mixture after mixing. Here is the chemical equation:

NaHCO₃ (aq) + HC₂H₃O₂ (aq) + (heat)——> CO₂ (g) + H₂O (l) + NaC₂H₃O₂ (aq)

Baking soda is sodium hydrogen carbonate, a base or alkaline. Vinegar is 5% acetic acid. The products are carbon dioxide, water, and sodium acetate. Sodium acetate, a base, is sometimes used for “salt and vinegar” flavor on snack foods. The pH scale is a measure of acidity. A pH less than 7 is an acid, higher than 7 is alkaline.

Can you explain how the reaction uses heat from the atmosphere? This is an endothermic reaction. A different process is used to burn fossil fuels and coal to emit heat (exothermic), which heats water to turn turbines.

Resource links

• http://www.wisc-online.com/Objects/ViewObject.aspx?ID=ELE806
  • Slide show from Wisconsin Online
• http://www.mbmg.mtech.edu/kids/make_a_volcano.htm
  • Let’s make a volcano from Montana State Exploring Earth Sciences
• http://chemistry.about.com/od/acidsbase1/a/red-cabbage-ph-indicator.htm
  • How to make red cabbage indicator from About Education
• https://www.exploratorium.edu/science_explorer/bubblebomb.html
  • Bubble bomb from the Exploratorium
• http://www.vernier.com/products/interfaces/labq2/
  • LabQuest2 from Vernier Software & Technology

Letʻs talk story

Children can easily do this experiment and practice measuring and observing. Chemical energy is conceptually different to learn from physicsʻ potential and kinetic energy. Currently, many “natural” cleaning recipes on the Internet use vinegar with baking soda. This experiment introduces the science of the reaction and can open the door to discussing conservation of energy and balancing chemical equations. I like to ask children what they think is happening when they see the bubbling and foaming – many think it’s boiling. These kind of events, and following up on what is really happening, is what makes science so fun!

I’ll be looking for comments below, or contact me at lisa [at] thecasabouquet[dot]com.

Sources

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