Is graphite oxide an acidic oxide

Oxides of carbon

Harmful non-metal oxides

A large part of the environmentally harmful emissions are oxides of non-metals such as sulfur, nitrogen and, in particular, carbon. These oxides are also referred to as "acid oxides" or "acid anhydrides".

We speak of emissions when substances from certain sources enter the atmosphere. It does not matter whether these substances come from natural sources (oceans, bogs, volcanism) or whether they are pollutants that humans produce (chimneys, heaters, car exhaust fumes). In addition to sulfur dioxide (SO2) and nitrogen oxides (NOx) also the greenhouse gas carbon dioxide (CO2) and the toxic carbon monoxide (CO). The disturbance of the natural equilibrium of the atmosphere through interference in the natural balance and through the emission of greenhouse gases intensifies the natural greenhouse effect and leads to global warming, which in turn is associated with numerous consequences.


Carbon monoxide

Carbon monoxide (CO) results from the incomplete combustion of carbon or its compounds when there is not enough oxygen for complete combustion. It is a colorless, flammable and very toxic gas that is almost insoluble in water. Industry uses CO as a reducing agent.


Carbon monoxide is a dangerous respiratory poison because it is chemically bound by the hemoglobin of the blood instead of oxygen and is therefore essential O for humans2 withholds. If large amounts of carbon monoxide enter the bloodstream via the lungs, it can cause death from asphyxiation. Symptoms of mild poisoning include headache, dizziness, and flu-like symptoms. Higher doses are highly toxic to the central nervous system and heart. The occupational exposure limit (OEL - previously: MAK value) is 30 ppm.

Carbon monoxide is contained in almost all combustion gases - from cigarette smoke to thermal power plants. When burned, carbon monoxide develops a great deal of heat from combustion.


In the laboratory, CO can be produced by decomposing formic acid:

$ \ mathrm {HCOOH \ quad \ longrightarrow \ quad CO + H_ {2} O} $


The disintegration is caused by the dehydrating effect of concentrated sulfuric acid, which is added dropwise to the formic acid.


carbon dioxide

Carbon dioxide (CO2) is an incombustible, acidic, colorless and odorless gas that dissolves well in water and has a much greater density than air. With basic metal oxides or hydroxides, it forms two types of salts called carbonates and hydrogen carbonates. Carbon dioxide is produced in combustion reactions when there is enough oxygen in the environment:


$ \ mathrm {C + O_ {2} \ quad \ longrightarrow \ quad CO_ {2} + 394 \ kJ} $


In the laboratory you can use CO2 by dripping hydrochloric acid onto marble (CaCO3) win:


$ \ mathrm {\ underbrace {CaCO_ {3} + H ^ {+} _ {(aq)} + Cl ^ {-} _ {(aq)}} _ {\ underset {\ large {+ hydrochloric acid}} {calcium carbonate }} \ longrightarrow \ underbrace {Ca ^ {+} _ {(aq)} + 2 Cl ^ {-} _ {(aq)}} _ {calcium chloride} + H_ {2} O + CO_ {2} \ uparrow} $


Carbon dioxide reacts with water in an equilibrium reaction to form carbonic acid (H.2CO3):


$ \ mathrm {CO_ {2} + H_ {2} O \ leftrightharpoons H_ {2} CO_ {3}} $


Fizzy mineral water is the result of such a reaction. In nature there is CO2 the starting product of photosynthesis. The air exhaled by humans contains 4% CO2 as the product of respiration in the cells, with the greatest CO2- Amount comes from the respiration of the microorganisms. In contrast, the proportion due to artificial CO2- Production due to technical processes is relatively low.


Figure 4 gives an overview of the turnover of carbon dioxide on earth. It can be seen that the CO2- The content of the atmosphere increases slightly. The consequences of this air change are known today as the greenhouse effect or global warming.



At temperatures above 1000 ° C, carbon dioxide is reduced from carbon to carbon monoxide in an equilibrium reaction:


$ \ mathrm {173 \ kJ + CO_ {2} + C \ quad \ rightleftharpoons \ quad 2 \ CO} $


This process takes place in the blast furnace process (Chapter 57).

CO2 is also produced during fermentation processes such as alcoholic fermentation. If you leave beer open for a long time, it loses its taste. To prevent this from happening when the keg is tapped, CO is pressed2 from a steel bottle into the beer barrel.

When carbon dioxide is introduced into lime water, calcium carbonate is formed (turbidity). This reaction serves as a Evidence for carbon dioxide.


$ \ mathrm {\ underbrace {Ca ^ {+} _ {(aq)} + 2 \ OH ^ {-} _ {(aq)}} _ {Kalkwasser} + CO_ {2} \ quad \ longrightarrow \ quad \ underbrace {CaCO_ {3} \ downarrow \} _ {\ underset {\ large (white \ precipitation)} {calcium carbonate}} + H_ {2} O} $


How carbon dioxide gets into the trade

Liquid carbon dioxide is sold in gray steel bottles. These must not be exposed to direct sunlight or stored next to radiators (risk of explosion due to expansion!). In technology, carbon dioxide is used as a refrigerant, because it changes from the solid state ("dry ice") directly to the gaseous state (sublimation). In everyday life you can experience sublimating dry ice in discos: The effective mists consist of subliming CO2.