The primary gas released during photosynthesis is oxygen (O2). During the process, plants, algae, and some bacteria convert carbon dioxide (CO2) and water (H2O) into glucose (C6H12O6) and oxygen, using sunlight as energy. This chemical reaction occurs primarily in chloroplasts, where chlorophyll captures light energy. Photosynthesis is essential for life on Earth, as it not only provides energy for plants but also produces oxygen, which is vital for most living organisms. The overall equation for photosynthesis is 6CO2 + 6H2O + light energy → C6H12O6 + 6O2.