Energy & Green Tech

Recycling – A batteries passport

Scientists at Oak Ridge National Laboratory have devised a method to identify the unique chemical makeup of every lithium-ion battery around the world, information that could accelerate recycling, recover critical materials ...

Energy & Green Tech

Turning seawater into stored energy

Afew years ago, Harvard chemist Daniel Nocera, along with collaborators from Harvard Medical School, created a system that uses sunlight to split water molecules and combine them with carbon dioxide from air to produce renewable ...

Energy & Green Tech

Sustainable biodiesel from neem tree trans-esterification

The neem tree, Azadirachta indica, also known as the Indian Lilac, is well known for its oil extracted from its seed and fruit. It has been used in traditional medicine but has also been investigated for the pest control ...

Energy & Green Tech

Engineers go microbial to store energy, sequester carbon dioxide

By borrowing nature's blueprints for photosynthesis, Cornell University bioengineers have found a way to efficiently absorb and store large-scale, low-cost renewable energy from the sun—while sequestering atmospheric carbon ...

Energy & Green Tech

Benefits of renewable energy vary from place to place

A new study from North Carolina State University finds that the environmental benefits of renewable power generation vary significantly, depending on the nature of the conventional power generation that the renewable energy ...

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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