News tagged with chemical composition
Unsustainable harvesting of Prunus africana tree threatens prostate treatment
Responding to the dwindling abundance of Prunus africana in the wild, a tree listed as "vulnerable to extinction" by the International Union for Conservation of Nature, a recent study by the World Agroforestry Centre identi ...
Mar 28, 2012 |
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The earliest stages of planet formation
(PhysOrg.com) -- Small dust particles in a disk of gas around a young star, according to current models, gradually coagulate during the first million years until kilometer-sized objects are formed. These in ...
Mar 26, 2012 |
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Artificial comet contains building blocks of life
The first molecules of life form naturally in comets, reveals a French-German study led by Uwe Meierhenrich and Cornelia Meinert at the Institut de Chimie de Nice and by Louis Le Sergeant d'Hendecourt at the ...
Space & Earth / Space Exploration
Mar 21, 2012 |
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Earth siblings can be different: Chemical clues on the formation of planetary systems
An international team of researchers, with the participation of IAC astronomers, has discovered that the chemical structure of Earth-like planets can be very different from the bulk composition of the Earth. ...
Feb 23, 2012 |
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Astronomers watch instant replay of powerful stellar eruption
Astronomers are watching the astronomical equivalent of an instant replay of a spectacular outburst from the unstable, behemoth double-star system Eta Carinae, which was initially seen on Earth nearly 170 ...
Feb 15, 2012 |
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Shear stiffness and friction mechanics of single-layer graphene measured for the first time
Researchers from the University of Bristol have measured and identified for the first time the stress and strain shear modulus and internal friction of graphene sheets. Graphene is a material that has many ...
Nanotechnology / Nanomaterials
Feb 14, 2012 |
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Hacking the SEM: Crystal phase detection for nanoscale samples
(PhysOrg.com) -- Custom modifications of equipment are an honored tradition of the research lab. In a recent paper, two materials scientists at the National Institute of Standards and Technology describe how ...
Jan 25, 2012 |
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Creation of database for promising adsorbents for decontamination of radioactive substances from nuclear power plants
(PhysOrg.com) -- NIMS is collecting basic data on natural minerals produced in various regions and inorganic materials with different chemical compositions as a tool for selecting suitable materials, and will make this information ...
Jan 13, 2012 |
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Cockroach 'let's hook up' chemical signal could benefit endangered woodpecker
A North Carolina State University discovery of the unique chemical composition of a cockroach signal -- a "Let's hook up" sex pheromone emitted by certain female wood cockroaches to entice potential mates ...
Dec 19, 2011 |
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Nitrogen from humans pollutes remote lakes for more than a century
Nitrogen derived from human activities has polluted lakes throughout the Northern Hemisphere for more than a century and the fingerprint of these changes is evident even in remote lakes located thousands of ...
Dec 15, 2011 |
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'Magnetic tongue' ready to help produce tastier processed foods
The "electronic nose," which detects odors, has a companion among emerging futuristic "e-sensing" devices intended to replace abilities that once were strictly human-and-animal-only. It is a "magnetic tongue" ...
Chemistry / Analytical Chemistry
Oct 26, 2011 |
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Sunlight changes aerosols in clouds
(PhysOrg.com) -- Today's climate models regard organic aerosols as static carbon-based molecules, but scientists at Pacific Northwest National Laboratory and the University of California, Irvine showed that ...
Space & Earth / Earth Sciences
Oct 12, 2011 |
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NEEM ice core drilling in Greenland provides comprehensive new results
The drilling through the ice sheet at NEEM (77 N, 51V) was completed in August and now scientists can begin to review whether the drilling was a success. 14 nations participated in the scientific work at NEEM, ...
Space & Earth / Earth Sciences
Oct 07, 2011 |
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First comet found with ocean-like water: New clues to creation of Earth's oceans
(PhysOrg.com) -- New evidence supports the theory that comets delivered a significant portion of Earth's oceans, which scientists believe formed about 8 million years after the planet itself.
Space & Earth / Space Exploration
Oct 05, 2011 |
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Puzzling comet composition solved?
For years comets have mystified scientists with their compositions that appear to have formed in both warm and cold environments, rather than in one location of a uniform temperature. But new research shows ...
Space & Earth / Space Exploration
Oct 05, 2011 |
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Empirical formula
In chemistry, the empirical formula of a chemical compound is a simple expression of the relative numbers of each type of atom in it, or the simplest whole number ratio of atoms of each element present in a compound. An empirical formula makes no reference to isomerism, structure, or absolute number of atoms. The empirical formula is used as standard for most ionic compounds, such as CaCl2, and for macromolecules, such as SiO2. The term empirical refers to the process of elemental analysis, a technique of analytical chemistry used to determine the relative amounts of each element in a chemical compound.
In contrast, the molecular formula identifies a numbers of each type of atom in a molecule, and the structural formula also shows the structure of the molecule.
For example, the chemical compound n-hexane has the structural formula CH3CH2CH2CH2CH2CH3, which shows that it has 6 carbon atoms arranged in a straight chain, and 14 hydrogen atoms. Hexane's molecular formula is C6H14, and its empirical formula is C3H7, showing a C:H ratio of 3:7. Different compounds can have the same empirical formula. For example, glucose, formaldehyde and acetic acid have the same empirical formula, CH2O. This is the actual chemical formula for formaldehyde, but acetic acid has double the number of atoms and glucose has six times the number of atoms.
For more information about Empirical formula, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
