Carbon dioxide

**Chemical and Physical Properties of Carbon Dioxide**:
– CO2 is a chemical compound with the formula CO2.
– It is a gas at room temperature and a greenhouse gas.
– Soluble in water, it forms carbonate and bicarbonate.
– CO2 levels in the atmosphere have risen due to burning fossil fuels.
– Essential for photosynthesis and the survival of life on Earth.
– CO2 molecule is linear and centrosymmetric.
– Carbon-oxygen bond length is 116.3pm.
– It has four vibrational modes observed in the infrared spectrum.
– In aqueous solutions, it forms carbonic acid.
– Colorless gas with odor at high concentrations.
– Density at standard conditions is around 1.98 kg/m3, denser than air.
– No liquid state below 0.51795 MPa; solid form known as dry ice.

**Industrial and Environmental Applications of Carbon Dioxide**:
– Used as an inert gas in welding and fire extinguishers.
– Pressurizing gas in air guns and oil recovery.
– Used as a supercritical fluid solvent in decaffeination.
– Byproduct of fermentation in bread, beer, and wine making.
– Added to carbonated beverages for effervescence.

**Regulation, Sequestration, and Chemical Reactions of Carbon Dioxide**:
– Excess CO2 emissions are absorbed by land and ocean sinks.
– Sequestered in rocks, coal, petroleum, and natural gas.
– Released into the atmosphere naturally by geological processes.
– CO2 is long-lived and mixes thoroughly in the atmosphere.
– CO2 is a potent electrophile with reactivity comparable to benzaldehyde.
– Reactions of nucleophiles with CO2 are often reversible.
– Strong nucleophiles like Grignard reagents react with CO2 to give carboxylates.
– CO2 serves as a ligand for chemical conversions in metal carbon dioxide complexes.

**Biological Role and Photosynthesis of Carbon Dioxide**:
– End product of cellular respiration in organisms.
– Essential for photosynthesis and carbon fixation in plants, algae, and cyanobacteria.
– Carbon fixation process incorporates atmospheric CO2 into organic molecules.
– Photosynthesis uses CO2 and water to produce sugars and oxygen.
– RuBisCO is crucial for carbon fixation in plants.
– Plants, algae, and cyanobacteria create energy-rich organic molecules through carbon fixation.

**Health Effects, Indoor Concentrations, and Transport in the Blood of Carbon Dioxide**:
– CO2 is not classified as toxic but can cause asphyxiation.
– Elevated CO2 levels can impact health and cognitive abilities.
– Indoor CO2 concentrations can exceed outdoor levels due to poor ventilation.
– Majority of carbon dioxide is converted to bicarbonate ions in the blood.
– Hemoglobin carries both oxygen and carbon dioxide in the blood.
– Carbon dioxide influences the transport of oxygen in the blood and respiratory regulation.