A new mathematical approach to understanding zeolites

Zeolites are a class of natural or manufactured minerals with a sponge-like structure, riddled with tiny pores that make them useful as catalysts or ultrafine filters. But of the millions of zeolite compositions that are ...

Can citric acid be a green alternative to protecting steel?

Nitric acid is currently the most widely used passivating solution to protect stainless steel from corrosion in industrial applications. But nitric acid is dangerous in multiple environmental, safety, and processes, due to ...

Geochemists measure new composition of Earth's mantle

What is the chemical composition of the Earth's interior? Because it is impossible to drill more than about ten kilometres deep into the Earth, volcanic rocks formed by melting Earth's deep interior often provide such information. ...

Mid-mass black hole hurls star across the Milky Way

An international team of astronomers has pinpointed the origin of a runaway high-velocity star named PG 1610+062 and determined that it was likely ejected from its birth cluster with the help of a mid-mass black hole (MMBH).

Analyzing the world's oldest woody plant fossil

Mapping the evolution of life on Earth requires a detailed understanding of the fossil record, and scientists are using synchrotron-based technologies to look back—way, way back—at the cell structure and chemistry of ...

Circulation of water in deep Earth's interior

Phase H is a hydrous mineral that is considered to be an important carrier of water into deep Earth. We determined the dissociation condition of phase H by a theoretical calculation based on quantum mechanics. Phase H decomposes ...

Synchronization of ice cores using volcanic ash layers

Thin, brownish layers of a thickness of about a millimeter or two are sometimes observed in the whitish/transparent ice cores. These brown layers consist of material originating from volcanic eruptions.

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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.

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