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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.
These characteristics make primary standards reliable for preparing standard solutions with an accurate concentration just by knowing the amount of compound and solvent used. Primary standard solutions are commonly used to determine the concentration of secondary standard solutions through titration .
Back titration is a titration done in reverse; instead of titrating the original sample, a known excess of standard reagent is added to the solution, and the excess is titrated. A back titration is useful if the endpoint of the reverse titration is easier to identify than the endpoint of the normal titration, as with precipitation reactions
Secondary standards are calibrated with reference to a primary standard. [2] The third level of standard, a standard which is periodically calibrated against a secondary standard, is known as a working standard. [2] Working standards are used for the calibration of commercial and industrial measurement equipment.
In that case, a constant ionic strength can be maintained, and [+] is known at all titration points if both [+] and [] are known (and should be directly related to primary standards). For instance, Martell and Motekaitis (1992) calculated the pH value expected at the start of the titration, having earlier titrated the acid and base solutions ...
KHP is slightly acidic, and it is often used as a primary standard for acid–base titrations because it is solid and air-stable, making it easy to weigh accurately. It is not hygroscopic . [ 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 ...
A new trend gaining popularity among people trying to lose weight is microdosing the diabetes medication Ozempic. Experts weigh the pros and cons of the practice.
The volumetric titration is based on the same principles as the coulometric titration, except that the anode solution above now is used as the titrant solution. The titrant consists of an alcohol (ROH), base (B), SO 2 and a known concentration of I 2. Pyridine has been used as the base in this case. One mole of I 2 is consumed for each mole of ...