Sour candy chemistry

Add candies to a baking soda solution, to confirm or predict which ones are the most and least sour.
Science content
Biology: Sensing, Organ Systems (4, 5, 6)
Chemistry: States of Matter, Properties of Materials (K-7)
Chemistry: Atoms, Molecules (3-7)
Chemistry: Chemical Changes (2, 7)
Lessons activity is in
  • candies of the same brand, some sour, some regular
  • tray with wells e.g. paint tray or ice cube tray
  • baking soda
  • small scoop or coffee stir stick
  • water in a squeeze bottle

Add a small scoop of baking soda to a well of the tray.
Squirt in water to dissolve the baking soda solution.
Add a candy to the baking soda solution. If it has a sour coating, it will make bubbles.

If appropriate, discuss the chemical reaction:
The baking soda (HCO2) reacts with the H of the sour coating to make carbon dioxide (CO2) gas.
Students can use molecular models to figure out the reaction: give them the starting molecules, ask them to make water (H2O) and figure out what other molecule is made. When they use up all the atoms and bonds, and fill all the holes on the atoms, they should arrive at CO2, which is a gas, and makes the bubbles that they see.

Grades taught
Gr 4
Gr 5
Gr 6
Teaching site
Brock Elementary