News tagged with chemical composition
Related topics: proceedings of the national academy of sciences , water
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.
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Research has suggested that compounds that give colorful fruits their rich hues, especially berries, promote health and might even prevent cancer. But for the first time, scientists have exposed extracts from numerous berries ...
Health Jan 28, 2013 | 5 / 5 (1) | 0
(Medical Xpress) -- Scientists have discovered that two common mango varieties contain natural compounds that may help to fight flab . . . in the part that most people throw away.
Health Jun 01, 2012 | 5 / 5 (1) | 0
A multi-university research group which includes several University of Notre Dame faculty and graduate students, has recently published a paper detailing new work on the analysis and dating of human bruises. The research, ...
Medical research Jan 26, 2012 | not rated yet | 0
Modifying stomach acid levels may not be enough to treat symptoms in neonates suspected of having gastroesophageal reflux disease. According to a study from Nationwide Children's Hospital, this is the first study to classify ...
Diseases, Conditions, Syndromes Aug 08, 2011 | not rated yet | 0
Chemical screening technologies will help doctors to monitor surgical patients before, during and after operations, providing better targeted care and treatment, say Imperial College London experts in an article published ...
Medical research May 18, 2011 | not rated yet | 0