什麼是CO2

則係二氧化碳
二氧化碳是空氣中常見的化合物，其分子由一個碳原子和兩個氧原子組成。

常壓下為無色、無臭、不助燃、不可燃的氣體。

能溶於水，略微溶於醇。

二氧化碳通常是由燃燒有機化合物、細胞的呼吸作用、微生物的發酵作用等所產生，植物在有陽光的情況下吸取二氧化碳，在其葉綠體內進行光合作用，產生碳水化合物和氧氣，氧氣可供其他生物進行呼吸作用，這種循環稱為碳循環(carbon cycle)。

二氧化碳是溫室氣體之一，可以把來自太陽的熱能鎖起來，不讓其流失，如果大氣中的二氧化碳含量過多，熱量更難流失，地球的平均氣溫也會隨之上升，這種情況稱為溫室效應。

二氧化碳的固體狀態是乾冰。

C 是碳元素的符號
O 是氧元素的符號
CO2 是二氧化碳的符號

二氧化碳lo

CO2係二氧化碳, carbon dioxide

二氧化碳
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Carbon dioxide,二氧化碳

CO2即係carbon dioxide 二氧化碳

carbon dioxide, chemical compound, CO2, a colorless, odorless, tasteless gas that is about one and one-half times as dense as air under ordinary conditions of temperature and pressure. It does not burn, and under normal conditions it is stable, inert and nontoxic. It will however support combustion of magnesium to give magnesium oxide and carbon. Although it is not a poison, it can cause death by suffocation if inhaled in large amounts. It is a fairly stable compound but decomposes at very high temperatures into carbon and oxygen. It is fairly soluble in water, one volume of it dissolving in an equal volume of water at room temperature and pressure; the resultant weakly acidic aqueous solution is called carbonic acid. The gas is easily liquefied by compression and cooling. If liquid carbon dioxide is quickly decompressed it rapidly expands and some of it evaporates, removing enough heat so that the rest of it cools into solid carbon dioxide “snow.” A standard test for the presence of carbon dioxide is its reaction with limewater (a saturated water solution of calcium hydroxide) to form a milky-white precipitate of calcium hydroxide.
Carbon dioxide occurs in nature both free and in combination (e.g., in carbonates). It is part of the atmosphere, making up about 1% of the volume of dry air. Because it is a product of combustion of carbonaceous fuels (e.g., coal, coke, fuel oil, gasoline, and cooking gas), there is usually more of it in city air than in country air. The natural balance of carbon dioxide in the atmosphere is growing from its stable level of 0.13% to a predicted 0.14% by the year 2000. It is anticipated that this extra carbon dioxide will fuel the greenhouse effect, warm the atmosphere, and further disrupt the natural carbon dioxide cycle (see global warming).

In various parts of the world—notably in Italy, Java, and Yellowstone National Park in the United States—carbon dioxide is formed underground and issues from fissures in the earth. Natural mineral waters such as Vichy water sparkle (effervesce) because excess carbon dioxide that dissolved in them under pressure collects in bubbles and escapes when the pressure is released. The chokedamp (see damp) of mines, pits, and old, unused wells is largely carbon dioxide. Carbon dioxide is a raw material for photosynthesis in green plants and is a product of animal respiration. It is also a product of the decay of organic matter.

Carbon dioxide has varied commercial uses. Its greatest use as a chemical is in the production of carbonated beverages; it provides the sparkle in carbonated beverages such as soda water. Formed by the action of yeast or baking powder, carbon dioxide causes the rising of bread dough. The compound is also used in water softening, in the manufacture of aspirin and lead paint pigments, and in the Solvay process for the preparation of sodium carbonate. In some fire extinguishers carbon dioxide is expelled through a nozzle and settles on the flame, smothering it. It also has numerous nonchemical uses. It is used as a pressurizing medium and propellant, e.g., in aerosol cans of food, in fire extinguishers, in target pistols, and for inflating life rafts. Because it is relatively inert, it is used to provide a nonreactive atmosphere, e.g., for packaging foods, such as coffee, that can be spoiled by oxidation during storage. Solid carbon dioxide, known as dry ice, is used as a refrigerating agent.

There are three principal commercial sources for carbon dioxide. High-purity carbon dioxide is produced from some wells. The gas is obtained as a byproduct of chemical manufacture, as in the fermentation of grain to make alcohol and the burning of limestone to make lime. It is also manufactured directly by burning carbonaceous fuels. For commercial use it is available as a liquid under high pressure in steel cylinders, as a low-temperature liquid at lower pressures, and as the solid dry ice.

CO2係二氧化碳,
CO係一氧化碳.

CO2是 二氧化碳。

CO2係解二氧化碳
姐係個英文簡稱...

Carbon dioxide is a chemical compound, normally in a gaseous state, and is composed of one carbon and two oxygen atoms. It is often referred to by its formula CO2. Carbon dioxide is present in the Earth's atmosphere at a concentration of approximately .000383 by volume (383 ppm) and is an important greenhouse gas due to its ability to absorb many infrared wavelengths of sunlight, and due to the length of time it stays in the atmosphere. It is also a major component of the carbon cycle. In its solid state, carbon dioxide is called dry ice. CO2 has no liquid state at normal atmospheric pressure.

Chemical and physical properties
Carbon Dioxide is normally a colorless, odorless and neutral gas. When inhaled at concentrations higher than the usual atmospheric level of 300-600 ppm (Parts Per Million; by volume) it can produce a sour taste in the mouth and a stinging sensation in the nose and throat. These effects result from the gas dissolving in the mucous membranes and saliva, forming a weak solution of carbonic acid. One may notice this sensation if one attempts to stifle a burp after drinking a carbonated beverage. Amounts above 5000 ppm are considered unhealthy, and those above about 50000 ppm are considered dangerous to animal life.


Carbon dioxide was first liquefied (at elevated pressures) in 1823 by Humphry Davy and Michael Faraday.[2] The earliest description of solid carbon dioxide was given by Charles Thilorier, who in 1834 opened a pressurized container of liquid carbon dioxide, only to find that the cooling produced by the rapid evaporation of the liquid yielded a "snow" of solid CO2.[3]