Dictionary of Chemistry [6th Ed.]

the slow release of equally toxic hy- drogen cyanide gas. potassium dichromate (potas- sium bichromate) An orange-red crystallin ...

separation from the iodate (which is also formed) by fractional crystalliza- tion. In solution it has the interesting property o ...

which is soluble in water and in ethanol but insoluble in diethyl ether; cubic; r.d. 1.80; m.p. 840°C. It is made industrially b ...

associated with the *activation en- ergy of the reaction. potentiometric titrationA titra- tion in which the end point is found ...

gauge that reads zero at atmospheric pressure. pressure gauge Any device used to measure *pressure. Three basic types are in use ...

to the air and the mixture contains hydrogen. The gas is used as a fuel in some industrial processes. product See chemical react ...

petroleum. Its main use is as bottled gas for fuel. propanedioic acid (malonic acid) A white crystalline dicarboxylic acid, HOOC ...

propene and used to make acrylic resins. propenyl group (allyl group) The organic group H 2 C=CHCH 2 –. propionaldehyde See prop ...

nature and extent of which is de- scribed as the secondary structure. The three-dimensional shape of the coiled or pleated polyp ...

curs in all atomic nuclei. See also hy- dron. protonic acid An *acid that forms positive hydrogen ions (or, strictly, oxonium io ...

adhesives, food packaging, and moulded articles. It is derived from the fungus Aureobasidium pullulans. pumiceA porous volcanic ...

tar. It is used in making other or- ganic chemicals. pyridoxineSee vitamin b complex. pyrimidine An organic nitrog- enous base ( ...

concave mirror onto a blackened foil to which a thermopile is attached. From the e.m.f. produced by the ther- mopile the tempera ...

Q QSARSee quantitative structure–activity relationship. QSMRSee quantitative structure–metabolism relation- ship. quadrivalentHa ...

nomenon in quantum mechanics in which a particle or system does not have a deÜnite state but exists as an intermediate form of t ...

theory the processes of emission and absorption are described in terms of the creation and disappearance of photons, with photon ...

quinhydrone electrode 450 q O O OH OH 2H + Quinhydrone electrode

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R racemateSee racemic mixture. racemic mixture (racemate)A mixture of equal quantities of the d- and l-forms of an optically act ...

gamma-radiation that produces ion pairs carrying 1 coulomb of charge of either sign in 1 kilogram of pure dry air. The former un ...

ation to produce chemical reactions. The radiation used includes alpha particles, electrons, neutrons, X-rays, and gamma rays fr ...