Carbon dioxide, also known as CO2, is a gas that makes up around 0.04% of the Earth's atmosphere, but plays an important role in maintaining the balance of other greenhouse gases and air temperature. This is because this gas (carbon dioxide) is produced when something is burned. Regardless of whether wood, coal or oil is burned - CO2 always rises into the air and compresses the atmosphere when something burns.

Carbon dioxide, also known as CO2, is a chemical compound of carbon and oxygen. It is a non-flammable, acidic and colorless gas. As it dissolves well in water, it is sometimes colloquially and incorrectly called "carbonic acid". It can form carbonates and hydrogen carbonates with basic metal oxides or hydroxides.

CO2 is a fundamental part of the global carbon cycle, a natural component of the air and an important greenhouse gas in the Earth's atmosphere. Human activities, especially the burning of fossil fuels, have increased the amount of carbon dioxide in the Earth's atmosphere from around 280 parts per million (ppm) at the beginning of industrialization to 407.8 ppm in 2018. In May 2019, the NOAA measuring station Mauna Loain Hawaii measured a monthly average of around 415 ppm, and the trend is rising. This increase intensifies the greenhouse effect and leads to the current global warming.

Carbon dioxide is a gas that is produced both during the combustion of carbon-containing substances and in the organisms of living organisms as a product of cellular respiration when there is a sufficient supply of oxygen. Plants, algae and some bacteria and archaea convert CO2 into biomass through fixation (carbon dioxide assimilation). During photosynthesis, glucose is produced from inorganicCO2 and water.

Carbon dioxide can have a toxic effect. However, the concentrations in the air or the quantities consumed when drinking lemonade, for example, are far from sufficient. CO2 has a variety of technical applications: For example, in the chemical industry. In solid form as dry ice, it is used as a coolant; supercritical carbon dioxide is used as a solvent and extraction agent.

Carbon dioxide (CO2) is a chemical compound consisting of one carbon atom combined with two oxygen atoms. It is a gas at room temperature and pressure, but can be solidified under high pressure. Carbon dioxide is produced by plants through photosynthesis and is essential for life on earth.

The Flemish chemist Johan Baptista van Helmont (1580-1644) observed that the mass of charcoal decreased during combustion because the mass of the remaining ash was less than that of the charcoal used. His interpretation was that the rest of the charcoal had turned into an invisible substance, which he called gas or spiritus sylvestre ("forest spirit"). It is not known when this gas was first referred to as carbon dioxide.

Carbon dioxide (CO2; formerly also known as "carbonic acid") was one of the first gases to be given the name "gas".

The Scottish physician Joseph Black (1728-1799) investigated the properties of CO2 more thoroughly. In 1754, he discovered that mixing calcium carbonate solutions with acids released a gas that he called fixed air. He found that this gas was heavier than air and did not support combustion processes. When he introduced this gas into a solution of calcium hydroxide, he was able to produce a precipitate. With this phenomenon, he showed that carbon dioxide was present in the breath of mammals and was released by microbiological fermentation. His work proved that gases can be involved in chemical reactions and contributed to the foundation of the phlogiston theory.

Black also applied his knowledge of gases to medicine, using them as anesthetics during operations. He also discovered carbon monoxide (CO), the toxicity of which he established in 1756; however, his discovery was not fully appreciated in history until much later, as there was little interest in his work at the time (Kennedy).

Carbon dioxide was used for many things in the past and is still used today. Joseph Priestley succeeded in producing soda water in 1771 by adding sulphuric acid to a lime solution and dissolving the resulting carbon dioxide in a beaker of water. The connection between carbon dioxide and carbonic acid had already been recognized by William Brownrigg. In 1823, Humphry Davy and Michael Faraday liquefied carbon dioxide by increasing the pressure. From 1820, Henry Hill Hickman performed operations on animals that were painless after inhaling carbon dioxide in order to achieve anesthesia. He also described the physiological processes during anesthesia. The first description of solid carbon dioxide comes from Adrien Thilorier, who opened a pressurized container of liquid carbon dioxide in 1834 and discovered that spontaneous evaporation occurs under cooling, resulting in solid CO2.