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A standard solution created from a secondary standard cannot have its concentration accurately known without stoichiometric analysis against a primary standard. An example of a secondary standard is sodium hydroxide , a hydroscopic compound that is highly reactive with its surroundings.
A primary standard in metrology is a standard that is sufficiently accurate such that it is not calibrated by or subordinate to other standards. Primary standards are defined via other quantities like length, mass and time. Primary standards are used to calibrate other standards referred to as working standards. [1] [2] See Hierarchy of Standards.
[4] [5] [6] It is also used as a primary standard for calibrating pH meters because, besides the properties just mentioned, its pH in solution is very stable. It also serves as a thermal standard in thermogravimetric analysis. [7] KHP dissociates completely in water, giving the potassium cation (K +) and hydrogen phthalate anion (HP − or ...
Standard units for length would be embedded in the cornerstones of churches or important public buildings, so that all people trading in an area could agree on the units. There is a three-level hierarchy of physical measurement standards. At the top of the tree are the master standards – these are known as primary standards.
Tris is also used as a primary standard to standardize acid solutions for chemical analysis. Tris is used to increase permeability of cell membranes. [ 13 ] It is a component of the Moderna COVID-19 vaccine [ 14 ] and the Pfizer-BioNTech COVID-19 vaccine for use in children 5 through 11 years of age.
Hydrochloric acid, also known as muriatic acid or spirits of salt, is an aqueous solution of hydrogen chloride (HCl). It is a colorless solution with a distinctive pungent smell. It is classified as a strong acid. It is a component of the gastric acid in the digestive systems of most animal species, including humans.
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Green Tea standard reference. Certified reference materials (CRMs) are 'controls' or standards used to check the quality and metrological traceability of products, to validate analytical measurement methods, or for the calibration of instruments. [1] A certified reference material is a particular form of measurement standard.