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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. The concentration of a standard solution made with sodium ...
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.
The next quality standard in the hierarchy is known as a secondary standard. 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 ...
A burette and Erlenmeyer flask (conical flask) being used for an acid–base titration.. Titration (also known as titrimetry [1] and volumetric analysis) is a common laboratory method of quantitative chemical analysis to determine the concentration of an identified analyte (a substance to be analyzed).
There are three levels of standards in the hierarchy of metrology: primary, secondary, and working standards. [20] Primary standards (the highest quality) do not reference any other standards. Secondary standards are calibrated with reference to a primary standard. Working standards, used to calibrate (or check) measuring instruments or other ...
Examples of primary time, (i.e., frequency standards) are caesium standards and hydrogen masers. The international second is based on the microwave frequency (9,192,631,770 Hz) associated with the atomic resonance of the hyperfine ground state levels of the caesium-133 atom in a magnetically neutral environment.
First step is to plot the absorbance(A) values of standard solution against molar concentrations (c) of the known solution. Then the best straight line is plotted, passing through the origin. The experimental points are plotted as per Beer’s law: A= E*c*l where E= molar extinction coefficient and l= optical path length usually 1 cm.
Pressure. A U tube filled with water is a primary instrument as the water column differential is unchangeable as water is a basic physical substance. It is accurate due to its nature. Similarly a liquid in glass thermometer is a primary instrument as temperature change causes change in height of mercury column differential of which is unchangeable.