 impressed when he began to see patterns forming that helped him solve the equations even more quickly. He gave up checking the equations with Lego bricks about 10 equations into our exercise.
After finishing the 20 equations I had written out for him, he expressed an interest in balancing equations using real chemical symbols that make up real molecules. I made a short list of 5 equations just for him to try out. He was able to transfer the knowledge he used with our made up chemical equations to real world equations very easily. And as a bonus, this gave us a chance to practice identifying elements by their chemical symbol and also the nomenclature of molecules.
After spending so much time doing math and worksheets, I thought it might be fun to see a chemical equation in action! I wrote the equation for the reaction of baking soda and vinegar and asked my son if he recognized any of the molecules and asked him if it was a balanced equation as written.
NaHCO3 + CH3COOH → CO2 + Na+ + H2O + CH3COO-
Note: Vinegar is a mixture of many different chemicals. It is typically 5% acetic acid dissolved in water, so the molecular formula for acetic acid is used in this equation.
This equation is balanced as written, but we wondered how we could prove that the equation is an accurate description of what took place. Usually we play with baking soda and vinegar in a way that will result in an uncontrolled eruption, but this time we wanted a smaller reaction that we could observe more closely. We combined a small amount baking soda and vinegar in resealable sandwich bag, and sealed it up to watch the bubbling reaction. What happens to the bag as the reaction takes place? How could you test the contents of the bag to validate the chemical equation? (Hint: O2 is necessary for flame, H2 causes an explosive pop of flame, CO2 will extinguish a flame)
We really enjoyed this activity. I initially worried that it might be a little advanced for my 8 year old son, but he surprised me with his enthusiasm and quick comprehension. A few days after we did this activity, I found a Lego “molecule” sitting on the dining room table with a legend defining Lego brick color to chemical symbol and the instructions to solve his Lego molecule’s chemical formula. I love when enthusiasm for learning something new is carried over into playtime on his own, it makes these activities worth it!