NASA opens sample taken from the Moon 50 years on

The Apollo missions to the Moon brought a total of 2,196 rock samples to Earth. But NASA has only just started opening one of the last ones, collected 50 years ago.

Mammals can breathe through anus in emergencies

Rodents and pigs share with certain aquatic organisms the ability to use their intestines for respiration, finds a study publishing May 14th in the journal Med. The researchers demonstrated that the delivery of oxygen gas ...

Why did Mars dry out? New study points to unusual answers

Mars once ran red with rivers. The telltale tracks of past rivers, streams and lakes are visible today all over the planet. But about three billion years ago, they all dried up—and no one knows why.

Human skin lipids found to repel bed bugs

University of Kentucky entomology researchers have found that skin triglycerides, or lipids, keep bed bugs from staying very long on human hosts. Their finding could lead to new management strategies for this important ...

Carbon dioxide reactor makes Martian fuel

Engineers at the University of Cincinnati are developing new ways to convert greenhouse gases to fuel to address climate change and get astronauts home from Mars.

Catalysts found to convert carbon dioxide to fuel

The goal of tackling global warming by turning carbon dioxide into fuel could be one step closer with researchers using a supercomputer to identify a group of "single-atom" catalysts that could play a key role.

Scientists develop a cool new method of refrigeration

Adding salt to a road before a winter storm changes when ice will form. Researchers at the Department of Energy's Lawrence Berkeley National Laboratory (Berkeley Lab) have applied this basic concept to develop a new method ...

page 1 from 40

Carbon dioxide

Carbon dioxide (chemical formula: CO2) is a chemical compound composed of two oxygen atoms covalently bonded to a single carbon atom. It is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state.

Carbon dioxide is used by plants during photosynthesis to make sugars, which may either be consumed in respiration or used as the raw material to produce other organic compounds needed for plant growth and development. It is produced during respiration by plants, and by all animals, fungi and microorganisms that depend either directly or indirectly on plants for food. It is thus a major component of the carbon cycle. Carbon dioxide is generated as a by-product of the combustion of fossil fuels or the burning of vegetable matter, among other chemical processes. Large amounts of carbon dioxide are emitted from volcanoes and other geothermal processes such as hot springs and geysers and by the dissolution of carbonates in crustal rocks.

As of March 2009[update], carbon dioxide in the Earth's atmosphere is at a concentration of 387 ppm by volume. Atmospheric concentrations of carbon dioxide fluctuate slightly with the change of the seasons, driven primarily by seasonal plant growth in the Northern Hemisphere. Concentrations of carbon dioxide fall during the northern spring and summer as plants consume the gas, and rise during the northern autumn and winter as plants go dormant, die and decay. Carbon dioxide is a greenhouse gas as it transmits visible light but absorbs strongly in the infrared and near-infrared.

Carbon dioxide has no liquid state at pressures below 5.1 atmospheres. At 1 atmosphere (near mean sea level pressure), the gas deposits directly to a solid at temperatures below −78 °C and the solid sublimes directly to a gas above −78 °C. In its solid state, carbon dioxide is commonly called dry ice.

CO2 is an acidic oxide: an aqueous solution turns litmus from blue to pink. It is the anhydride of carbonic acid, an acid which is unstable and is known to exist only in aqueous solution.

CO2 is toxic in higher concentrations: 1% (10,000 ppm) will make some people feel drowsy. Concentrations of 7% to 10% cause dizziness, headache, visual and hearing dysfunction, and unconsciousness within a few minutes to an hour.

This text uses material from Wikipedia, licensed under CC BY-SA