Airy Acidification
Students learn how greenhouse gases contribute to ocean acidification.
Human actions contributing to climate change have added enormous amounts of the greenhouse gas carbon dioxide into the atmosphere, which then diffuses and reacts with the water in the ocean, raising its acidity level, in a process called ocean acidification.
What You Need
Materials:
- 10oz clear plastic cups or beakers (2)
- 3oz cup
- Covers for large cups (e.g., petri dishes) (2)
- Tape
- Measuring spoons
- Cabbage juice acid-base indicator
- Baking soda
- White vinegar
- White paper (a few sheets)
Guide:
Safety Notes
Ensure you are familiar with Let's Talk Science's precautions with respect to safe delivery of virtual outreach to youth.
What To Do
Pre-Activity Prep
- Prepare cabbage juice indicator (instructions found here)
Instructions
- Begin by adding about 3 tbs. (45 mL) of cabbage juice indicator to each large clear cup.
- Add 1/2 tsp. of baking soda to the small cup.
- Carefully tape the small cup inside one of the larger cups, so that the bottom does not touch the liquid, and the upper rim is below the rim of the larger cup. Do not spill any baking soda into the cabbage juice. The other large cup will be the control, so nothing will be added to it.
- Arrange the cups on some white paper so that the colour change will be easier to see. Place a sheet of paper below and behind the cups to really see the difference.
- Carefully add 1 tsp. (5mL) of white vinegar to the small cup with the baking soda, being careful not to spill any into the cabbage juice. Quickly cover both large cups and watch for the indicator to change colours.
- The cabbage juice indicator should change from purple to pink and the change will be the most visible along the surface.
Discovery
Mixing baking soda and white vinegar creates carbon dioxide gas (CO2). When CO2 reacts with water (H2O), it creates carbonic acid (HCO2), which then breaks down into hydrogen ion (H+) and bicarbonate (HCO3-). The extra hydrogen ions make the water more acidic.
Ocean acidification is a major issue, especially for marine creatures with shells and corals. Shells and corals are made of calcium carbonate, which can be weakened and dissolved when acidity is raised. It also affects fish health. When one species is impacted, it can disrupt the entire food web.
What's Happening?
Mixing baking soda and white vinegar creates carbon dioxide gas (CO2). When CO2 reacts with water (H2O), it creates carbonic acid (HCO2), which then breaks down into hydrogen ion (H+) and bicarbonate (HCO3-). The extra hydrogen ions make the water more acidic.
Why Does It Matter?
Ocean acidification is a major issue, especially for marine creatures with shells and corals. Shells and corals are made of calcium carbonate, which can be weakened and dissolved when acidity is raised. It also affects fish health. When one species is impacted, it can disrupt the entire food web.