The slowest step in a mechanism, the step that determines the overall rate of reaction.
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Third Law of Thermodynamics
The entropy of a hypothetical pure, perfect, crystalline sustance at absolute zero temperature is zero.
yield
The quantity of product formed by the interaction of two or more substances, generally expressed as a percentage of the quantity obtained to that theoretically obtainable.
Catalyst
A substance that speeds up a chemical reaction without being consumed itself in the reaction.
A substance that alters (usually increases) the rate at which a reaction occurs.
How to make crystal glass
From history we know that the idea of creating crystal belongs to the British: they were the first to add lead oxides to the charge material, and as a result got glass with unusual “voice”, transparency and sparkling faces. Classical crystal contains 24% of lead oxide, but there are products with a higher content of up to 30%.
Enantiomer
One of the two mirror-image forms of an optically active molecule.
Buret
A piece of volumetric glassware, usually graduated in 0.1-mL intervals, that is used to deliver solutions to be used in titrations in a quantitative (dropwise) manner.
Heat of Solution
The amount of heat absorbed in the formation of solution that contains one mole of solute, the value is positive if heat is absorbed (endothermic) and negative if heat is released (exothermic).
yttrium
A rare trivalent metallic element, found in gadolinite and other minerals. Symbol: Y, at. wt.: 88.905, at. no.: 39, sp. gr.: 4.47. Cf."rare-earth element."
Yttrium has a silver-metallic luster and is relatively stable in air unless finely divided. Turnings of the metal, however, ignite in air if their temperature exceeds 400oC. Yttrium oxide is one of the most important compounds of yttrium and accounts for the largest use. It is widely used in making YVO4 europium, and Y2O3 europium phosphors to give the red color in color television tubes.
Alcohol
Hydrocarbon derivative containing an --OH group attached to a carbon atom not in an aromatic ring. Alcohols are a class of organic compounds containing the hydroxyl group, OH, attached to a carbon atom.
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| Chemical Week - Daily news and product updates for professionals in the chemical industry. |
| American Chemistry Council News and Media - Provides chemistry business and industry news, updated issue briefs, fact sheets, press releases, media contacts and other resources. |
| About Chemistry - News articles, periodic tables, educational resources, newsletters, and annotated links. |
| General Chemistry Online - Rich resource for students and teachers of introductory chemistry. Includes interactive course guides and tutorials, an exam survival guide, reference tables, self-grading quizzes and exams, a searchable glossary, a question and answer board, answers to over 300 frequently asked questions, and a chemical trivia quiz. |
| Chem4Kids - Learn about chemistry including matter, atoms, and reactions. Includes online quizzes. |
| Chemistry & Environmental Dictionary - Contains definitions for many chemistry, environmental and other related technical terms and acronyms. |
| EDF Chemical Scoreboard - Toxic Release Inventory data for the US. Sources and amounts of toxic chemicals released to air and water. Also has information on health effects and other topics. |
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