At-Home STEM Activities: Kitchen Chemistry--Honeycomb Candy
Most of us have probably seen or created a baking soda-vinegar volcano. The fizzy eruption occurs due to an acid-base chemical reaction. You can read more about acids, bases, and the pH scale on this blog post.
The acid-base reaction is not the only type of chemical reaction, though. To name a few, there are synthesis reactions that create new chemicals, combustion reactions that create heat, and decomposition reactions that break down chemicals. Decomposition reactions are the opposite of synthesis reactions, taking one chemical substance and splitting it into two or more compounds. To cause a decomposition reaction, you need to add a lot of energy to a chemical compound, since most compounds are relatively stable and won’t spontaneously decompose. The forms this energy can take includes heat, light, radiation, and electricity.
One chemical substance that decomposes with the addition of heat is a component of our familiar volcano experiment: baking soda, also know as sodium bicarbonate. The chemical formula for baking soda is NaHCO3 (Na = Sodium, H = Hydrogen, C = Carbon, O = Oxygen [the 3 means there are 3 oxygen atoms]), and, when it reaches temperatures above 176°F, baking soda breaks down into sodium carbonate (Na2CO3), water (H20), and carbon dioxide (CO2).
The decomposition of baking soda is one you’ve probably experienced since it’s a reaction that is used in cooking. Many recipes for cakes and quick breads call for baking soda since while the batter is cooking, the baking soda will decompose, releasing carbon dioxide and providing rise to the baked good.
Let’s see the decomposition of baking soda in action through the making of a sweet treat!
Honeycomb Candy
Recipe adapted from The Spruce Eats
Ingredients:
2 tablespoons honey
1/4 cup light corn syrup
1 cup sugar
1 1/2 teaspoons of baking soda (generous scoops)
2 tablespoons of water
Chocolate chips (optional)
Materials:
Parchment paper
9 inch-by- inch pan
Non-stick cooking spray
Pastry brush
Candy thermometer or electric probe thermometer
Binder clip (optional)
Whisk
Instructions:
1. Prepare your pan by lining it with parchment paper. Lightly spray the parchment paper with non-stick cooking spray.
2. Combine the sugar, corn syrup, honey, and water in a large saucepan. You want to use a pan large enough for the mixture to triple in size. Stir everything together until the sugar is thoroughly moistened. Using a wet pastry brush, wipe down the sides of the pan to clean off stray sugar crystals.
3. Clip the thermometer to the side of the pan. We used a binder clip to attach the probe of our electric thermometer to the pan. If you’re using an electric thermometer, make sure the tip of the thermometer is within the sugar mixture and not touching the bottom of the pan. Don’t have a thermometer? Here’s how to test candy temperatures without a thermometer.
4. Cook the sugar mixture over medium-high heat, without stirring, until the temperature reaches 300°F. Be sure to keep an eye on the temperature, the candy can burn very quickly at this high of heat!
5. Once it reaches 300°F, remove the candy from the heat and add the baking soda all at once. If using an electric probe thermometer, carefully remove the probe—make sure not to touch the sugar; hot sugar can leave a severe burn. Whisk to incorporate the baking soda, being very careful as it will foam up fast. As soon as the baking soda is mixed in, pour the candy into the prepared pan.
6. Allow to cool and harden completely. Remove from the pan and break the honeycomb into small pieces. Observe the bubbly texture formed by the carbon dioxide released from the baking soda!
Optional: Dip the pieces into chocolate—melt the chocolate chips in a microwave-safe bowl, heating and stirring in 30-second intervals. Using two forks, dip the piece of candy into the chocolate and refrigerate until set.
Honeycomb candy is best when it’s eaten within 24 hours, since it will draw moisture from the air and lose its crunch. If kept in a airtight container, the candies will last a few days after making them.
