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R-22 use is being phased out in developing countries, where it is largely used for air conditioning applications. R-22 is prepared from chloroform: HCCl 3 + 2 HF → HCF 2 Cl + 2 HCl. An important application of R-22 is as a precursor to tetrafluoroethylene. This conversion involves pyrolysis to give difluorocarbene, which dimerizes: [3]
According to ASHRAE standard 34, the R-number of a chemical refrigerant is assigned systematically according to its molecular structure and has between two and four digits. If there are carbon -carbon multiple bonds , there are four digits in all: the number of these bonds is the first digit and the number of carbon atoms minus one (C-1) is next.
This type of diagram could be called temperature-luminosity diagram, but this term is hardly ever used; when the distinction is made, this form is called the theoretical Hertzsprung–Russell diagram instead. A peculiar characteristic of this form of the H–R diagram is that the temperatures are plotted from high temperature to low temperature ...
Another type of binary phase diagram is a boiling-point diagram for a mixture of two components, i. e. chemical compounds. For two particular volatile components at a certain pressure such as atmospheric pressure , a boiling-point diagram shows what vapor (gas) compositions are in equilibrium with given liquid compositions depending on temperature.
In 1909, the Danish chemist Søren Peter Lauritz Sørensen introduced the concept of pH at the Carlsberg Laboratory, [4] originally using the notation "p H•", with H• as a subscript to the lowercase p. The concept was later revised in 1924 to the modern pH to accommodate definitions and measurements in terms of electrochemical cells.
Crawford has represented Planned Parenthood of Wisconsin in addition to the Madison teachers union in their lawsuit over Act 10, a policy passed under former Gov. Scott Walker (R) that curtailed ...
Bake, rotating the baking sheet halfway through cooking, until golden brown on top and around the edges, 20 to 22 minutes. Remove the baking sheet from the oven. Let the macaroons cool for 5 ...
A former TD Bank employee based in Florida was arrested and charged with facilitating money laundering to Colombia, New Jersey's attorney general said on Wednesday, in the first such arrest since ...