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acidimetry
Значение термина acidimetry в knolik
acidimetry - Acidimetry
acidimetry - Chemical process of measuring the amount or strength of acid in solid or liquid substances. If the acid is known to be pure, its specific gravity may give sufficient indication of the strength of the acid, or this may be ascertained by the quantity of alkali needed exactly to neutralise or destroy the acidity. The process being reversible is also known as alkalimetry.
By taking a known amount of a pure alkali, such as sodium carbonate, and neutralising with it the acid of unknown strength, it is easy to calculate, from the chemical reaction, the amount of acid that was present. If on the other hand, a definite quantity of pure oxalic acid has been used to neutralise a solution of an alkali, the quantity of alkali present can be ascertained. It is necessary that the identity of the substance which is being tested should be established previously by chemical analysis. The test solutions used are called standard or normal solutions. They are prepared upon such a basis that they bear a relation to the molecular weight of the chemical employed. Only such substances are used for test solutions as can be obtained in a state of purity and remain unaltered in strength for a reasonable length of time.
As both the test solution and the substance that is being tested may be colourless, and afford no visible indication of the neutrality point, certain substances are employed which change colour according as the liquid is acid or alkaline. These are called indicators, among the best-known being litmus—red with acids, blue with alkalis; cochineal, yellowish-red with acids, purple with alkalis: and phenol-phthalein, colourless with acids, red with alkalis. The choice of the indicator depends upon the nature of the test that is being made. If the acidimetry is conducted with solutions, and the relative volumes of the liquids furnish the data required, the method is called volumetric. Where the weight of the resulting reaction is the factor taken into account, the process is called gravimetric.
Рядом со словом acidimetry в knolik
| acid | В начало буква "" буквосочетание "" | acidosis |
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