Search results
Results from the WOW.Com Content Network
The Food Protection Committee started in 1961 to provide objective quality standards for food-grade chemicals. Parts of the first edition were published in loose-leaf form between 1963 and 1966. The scope of the first edition is limited to substances amenable to chemical characterization or biological standardization which are added directly to ...
Food contact material pictogram (left) on a plastic food container in Hong Kong. Food contact materials or food contacting substances (FCS) [1] [2] are materials that are intended to be in contact with food. These can be things that are quite obvious like a glass or a can for soft drinks as well as machinery in a food factory or a coffee machine.
In general, pK a values in water and organic solvent diverge significantly when the anion is capable of hydrogen bonding. For instance, in the case of water, the values differ dramatically: the pK a in water of water is 14.0, [15] while the pK a in DMSO of water is 31.4, [16] reflecting the differing ability of water and DMSO to stabilize the ...
In chemistry, chemical stability is the thermodynamic stability of a chemical system, in particular a chemical compound or a polymer. [ 1 ] Chemical stability may also refer to the shelf-life of a particular chemical compound; that is the duration of time before it begins to degrade in response to environmental factors.
The IUPAC acknowledges the three divergent definitions of carbonium ion and urges care in the usage of this term. For the remainder of this article, the term carbonium ion will be used in this latter restricted sense, while non-classical carbocation will be used to refer to any carbocation with C–C and/or C–H σ-bonds delocalized by bridging.
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
An elevated water tank, also known as a water tower, will create a pressure at the ground-level outlet of 1 kPa per 10.2 centimetres (4.0 in) or 1 psi per 2.31 feet (0.70 m) of elevation. Thus a tank elevated to 20 metres creates about 200 kPa and a tank elevated to 70 feet creates about 30 psi of discharge pressure, sufficient for most ...
Allylic and benzylic compounds undergo more selective oxidations. Alkyl groups on a benzene ring are oxidized to the carboxylic acid, regardless of its chain length. Benzoic acid from toluene , terephthalic acid from para - xylene , and phthalic acid from ortho - xylene are illustrative large-scale conversions.