A primary standard is a measurement that is used in the calibration of working standards. A primary standard is chosen owing to its accuracy and its stability when exposed to other substances. Primary standards can be measured in terms of metrics including length, time or mass.
Safeopedia Explains Primary Standards
Primary standards are widely used in analytical chemistry. In this instance, a reagent that is easily weighed, has low reactivity with other substances, is pure and unlikely to change in weight when exposed to humid conditions and has a high equivalent weight is chosen. Less important factors that are taken into account include the availability of the substance chosen as primary standard and low toxicity levels to reduce risk. Titration acids and redox titrations are examples of primary standards.
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In metrology (the science of measurement), a standard (or etalon) is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the fundamental reference for a system of weights and measures, against which all other measuring devices are compared.
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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.
A primary standard is a reagent that is extremely pure, stable, has no water of hydration and has a high molecular weight . Some primary standards are sodium carbonate, potassium hydrogen iodate, potassium dichromate, oxalic acid etc.
It defines primary standards as highly pure, stable chemicals that can be weighed easily and used directly for standardization. Secondary standards have lower purity and stability than primary standards but can be used indirectly after standardization against a primary standard.
A primary standard reference material is an ultra high purity grade compound used in analysis involving assay, identification or purity tests. It can be a single compound or a mixture having the analyte of interest in a specified and certified amount.
A primary standard material should be extremely pure which means that it should be a chemical of high grade of purity, preferably 99.98%. In a chemistry lab you will come across chemicals of different grade of purity. If you check the label you will notice a number with percentage termed as purity.
→ It is an incredibly pure substance: The primary standard materials should have a high degree of purity, especially 99.99%, meaning they must be a chemical that has been prepared from very pure materials. There are various grades of purity of chemicals in chemistry labs.
“A reference standard (i.e., primary standard) may be obtained from the USP/NF or other official sources (e.g., CBER, 21 CFR 610.0). A working standard (i.e., in-house or secondary standard) is a standard that is qualified against and used instead of the reference standard.”
A set of gauge blocks are used as a working standard to check the calibration of measurement tools such as micrometers. An example of a primary standard was the international prototype of the kilogram (IPK) which was the master kilogram and the primary mass standard for the International System of Units (SI).
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.
A primary standard is a chemical that is stable and pure not in the form of hydrate.The secondary standard is a solution/reagent that is prepared against the primary standard. It is mostly prepared in the laboratory.
Primary standards are typically used in titration to determine an unknown concentration and in other analytical chemistry techniques. ... The reaction confirms that the solution is at a specific concentration. Primary standards are often used to make standard solutions, solutions with a precisely known concentration.
HCl is a secondary standard solution. It is made by dissolving hydrogen chloride gas in water. So the concentration or strength of hydrochloric acid varies depending upon the external conditions.
It is not suitable for the primary standards because they absorb the moisture from the atmosphere. It also absorbs carbon dioxide from the atmosphere. Hence, NaOH is not a primary standard because it has no quality of primary standard.
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