Here's why:
* Photosynthesis requires CO2: Plants need carbon dioxide to make their food (glucose) during photosynthesis. The reaction uses CO2 along with water and sunlight.
* Air contains CO2 but not enough: While the air around us contains CO2, the concentration is relatively low. This might not be sufficient for optimal photosynthesis in a controlled experiment.
* Baking soda releases CO2: When sodium hydrogen carbonate (NaHCO3) dissolves in water, it decomposes and releases carbon dioxide:
* 2NaHCO3(aq) → Na2CO3(aq) + H2O(l) + CO2(g)
* Stable source of CO2: The baking soda solution provides a steady source of CO2 for the plant, ensuring that the experiment isn't limited by the availability of this key reactant.
How it's used in experiments:
* The plant (often a water plant like Elodea) is placed in the beaker with the baking soda solution.
* The beaker is usually sealed or covered to keep the CO2 concentration high.
* The rate of photosynthesis can be measured by observing factors like oxygen production (using a test tube and collecting the gas), or by measuring changes in the plant's starch content.
Important Note: While baking soda provides a good source of CO2, it's important to use a dilute solution to avoid harming the plant. The concentration should be adjusted based on the specific experiment and plant type.
