Is CO2 inert

Answer 1

CO₂ is an acidic oxide. Whether or not CO₂ can be considered "inert gas" depends on a number of factors. The most obvious of which being phase. Dry ice, for instance, is solid CO₂ & can't very well be considered an "inert gas". At temperatures below 300C, gaseous CO₂ can be considered "inert gas" as is commonplace in the food industry. However, at higher pressures CO₂ & H₂O combine to form aqueous H₂CO₃ (carbonated water). Also, gaseous CO₂ is readily broken down into component elements during photosynthesis. At temperatures exceeding 300C a reaction occurs between CO₂ & hydrogen know as the Sabatier reaction. Elemental hydrogen exists only in trace quantities within Earth's atmosphere, so this reaction is quite rare outside the lab. CO₂ is often mistakenly called "inert gas" by those in the welding industry. CO₂ is actually an 'active shielding gas' in this context as the welding arc causes electron dissociation, converting CO₂ into carbon monoxide & oxygen. The released oxygen generates heat, thus making CO₂'s role "active". Meanwhile, excess CO₂ "shields" the molten 'puddle' from unwanted atmospheric gas. Adding argon to the mix creates a 'semi-inert shielding gas', but that's for another lesson. Generally speaking, the only truly 'inert gases' are group 18 (noble gasses) & even they have their limits.