This chemical reaction lab challenge tests kids by putting their analytical, measuring, and hypothesis-making skills to the test!
By the time kids get to middle school age, they’ve played with vinegar and baking soda enough to know it can make some spectacular fizzes. This lab teaches kids the basics, the chemistry behind what happens when you add a mild acid to sodium bicarbonate (baking soda, use the real chemical name if you can!), and encourages the kids to take precise steps to figure out exactly how much of each reactant is needed to get the fizz to reach a set height.
There are no fancy materials in this chemical reaction lab; citric acid can be bought easily online, and you may even be able to find it in the pickling section of your grocery store. The primary safety concern here is that kids are following the lab safety rules, and especially have goggles on at all times.
Sodium bicarbonate (baking soda)
Glass test tube with fitted rubber stopper
1 mL measuring spoon (1/4 tsp)
Clear plastic vials
Small measuring cups
Plastic cups enough for 1 for each student.
Prepare for the Chemical Reaction Lab Challenge
- Prepare enough detergent solution (5 ml of liquid dish soap to 30 ml of water) for all kids to have a small amount
- Fill small 1-ounce containers with about 1 tsp sodium bicarbonate (enough for each student to have one)
- Fill small 1-ounce containers with 1 tsp citric acid (enough for each student to have one)
- ASK kids to describe the difference between a chemical and physical change.
- ASK kids what some evidence of a chemical change.
- DISCUSS Where in nature can we find chemical changes? How about volcanoes erupting? Remind students that when volcanoes erupt, carbon dioxide (and other gasses) are released into the magma. Nobody can control the amount of CO2 that’s released, but in a lab, we can control a chemical reaction.
- TELL students that volcanoes release carbon dioxide that has been trapped in magma deep within the earth. As the magma gets close to the surface, the pressure is reduced and the gas is released. These gasses can be produced in other ways, like with a chemical reaction. As you watch this demo, look for signs of a chemical reaction.
- Place 1 mL of citric acid into the test tube.
- Use graduated dropper to add 1 ml of water to the tube.
- Add 1 mL of sodium bicarbonate to the tube and quickly cap it with the stopper.
- Hold the tube straight up.
- ASK the kids what happened? The citric acid and baking soda reacted and made new chemicals. How do we know that something new was formed? Answer – bubbles form that weren’t there before and something pushed the stopper out of the tube
- ASK what type of gas was formed? Answer – Carbon dioxide
- ASK where does the carbon dioxide gas come from? Answer – it is made from atoms from the citric acid and baking soda.
Chemical Reaction Lab Challenge
- Do a demo to introduce students to the chemistry challenge.
- Tell students that you’re going to make an acid solution using citric acid and add it to baking soda. Tell them that you will also add a drop of detergent so that the bubbles formed during the reaction will last longer. This will create a foam that will give you a sense of how much carbon dioxide is being produced. Tell students that you’re using very specific amounts to keep the foam from rising too high.
- Have a detergent solution on hand (add 5 ml of liquid dish soap to 30 ml of water).
- Measure 5 ml of water and pour it into a small cup.
- Add 1 mL of citric acid and swirl.
- Add 1 drop of detergent solution and swirl.
- Add 1 mL of sodium bicarbonate to the vial.
- Pour the citric acid and detergent solution into the vial so that it mixes well with the baking soda.
- Stand the vial upright in a clear plastic cup.
- Question: Here’s your chemical reaction lab challenge. To make just the right amount of foam so that it rises all the way to the top of the vial without overflowing. PLEASE test this ahead of time as your results will vary depending on the size of your scoops, their precision in measuring, and the size of vial you’re using.
- Once the kids have had some time to puzzle this over, have them work in pairs to collaborate. Explain that collaboration is an important part of what scientists do daily.
Clean up for this chemical reaction lab challenge is easy: solids can be put into the trash, plastic containers can be rinsed and recycled, and liquids can go down the drain with plenty of running water.