Why primary standard substances are used to make standard solutions

$\begingroup$ KHP would be a primary standard in an acid base reaction. It can be obtained in high purity, and dried in an oven so that a given weight of KHP has a known amount of acid. You'd use the KHP and titrate with NaOH. The NaOH solution would then have a known value and be a secondary standard since its value was dependent on the KHP. $\endgroup$ A primary standard is critical for an analytical result. If we dissolve a known mass of a material into a known volume, we must be able to know its concentration with confidence. Such a standard must be easily made very pure (> 99.95%), it should not decompose, and it must be fairly robust to say heating or vacuum. We use such standard solutions as, for example, titrants. This is surprisingly hard to come by, and so we say that secondary standards are materials that do not meet these strict criteria. Say you want to titrate a sulfuric acid solution for quantitative work, you could use a known concentration of NaOH or KOH and volumetrically determine the concentration of the sulfuric acid solution. In fact, dissolving pellets of these particular bases in a known volume of water is not sufficient to calculate concentration with any confidence in analytical work because the solids are contaminated with carbonate from atmospheric CO$_2$. In general these carbonates contaminate alkaline solutions quite readily through this reaction: $\ce$ was used in mineralogical surveys of uranium prior to the Manhattan project, where better ...

A primary standard in In chemistry [ ] Standards are used in • High • Stability (low • Low • High • Non-toxicity • Ready and cheap availability (The last two are not as essential as the first four.) Some examples of primary standards for • • • 3) for standardisation of • • • • • Such standards are often used to make See also [ ] • References [ ] • ^ a b Skoog, Douglas A., Donald M. West and F. James Holler. "Fundamentals of Analytical Chemistry 8th ed." Harcourt Brace College Publishers. 1995 • Holt Science and Technology: Physical Science. Ed. Rinehart and Winston, Inc. Holt. Holt McDougal (July 2000). • • European Pharmacopoeia, chapter 4.2.1 External links [ ] •

Table of Contents • • • • • • What are the requirements for a primary standard? A good primary standard meets the following criteria: • Has a high level of purity. • Has low reactivity (high stability) • Has a high equivalent weight (to reduce error from mass measurements) • Is not likely to absorb moisture from the air (hygroscopic), to reduce changes in mass in humid versus dry environments. • Is nontoxic. What are the essential properties for a primary standard in a titration? These characteristics include high purity, low reactivity with the air or surrounding environment, low hygroscopicity, large molar mass and a predictable reactivity. What is the properties of a good primary standard? Characters of a good primary standard include: high purity, low reactivity with the air or surrounding environment, low hygroscopicity, large molar mass, a predictable reactivity and readily available. What are primary standards and what are its properties? A primary standard is a highly pure and stable chemical reagent used to prepare standard solutions, usually for titration and making secondary standards and dilutions. In chemistry, a primary standard is a reagent that is very pure, stable, not hygroscopic, and has a high molecular weight. What are primary standards? 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 ...

Standard solutions are used in analytical chemistry to determine the concentration and/or content of a substance. They have several scientific, medical, and industrial applications. Standard solutions are classified either as primary solutions or secondary solutions . Primary standard solutions are prepared from a standard substance (solute). The substance is carefully weighed based on its molar mass and dissolved to a specific volume of pure water , which is known as the weighing method of preparation. Secondary standard solutions are prepared from primary standard solutions. As a primary solution has a known concentration, the secondary solution can be prepared through the dilution method . In this post: • • • • • The Uses of Standard Solutions in Industry In industry, standard solutions are primarily employed for quality control and environmental safety compliance purposes. Standard solutions are often used to calibrate the accuracy and precision of chemical monitoring instruments. For instance, they can help ensure the apparatus responsible for measuring calories and electrochemical and turbidity parameters are working correctly. Standard solutions can also determine or rule out the presence of certain pollutants in water. As a result, they’re commonly used to analyse drinking water and wastewater. Standard solutions are commonly used to analyse drinking and wastewater. We’ve discussed their industrial uses, but what are examples of standard solutions? Some of the most...

A solution of accurately known concentration, prepared using standard substances in one of several ways. A primary standard is a substance of known high purity which may be dissolved in a known volume of solvent to give a primary standard solution. If @S06026@ is used to establish the strength of a @T06386@, it is called a secondary standard solution. The term secondary standard can also be applied to a substance whose active agent contents have been found by comparison against a primary standard. Concentrations of standard solutions may be expressed in \(\text\), or in terms more closely related to those used in specific titrations (as titres).

\( \newcommand\) • • • To standardize an analytical method we use standards that contain known amounts of analyte. The accuracy of a standardization, therefore, depends on the quality of the reagents and the glassware we use to prepare these standards. For example, in an acid–base titration the stoichiometry of the acid–base reaction defines the relationship between the moles of analyte and the moles of titrant. In turn, the moles of titrant is the product of the titrant’s concentration and the volume of titrant used to reach the equivalence point. The accuracy of a titrimetric analysis, therefore, is never better than the accuracy with which we know the titrant’s concentration. See Primary and Secondary Standards There are two categories of analytical standards: primary standards and secondary standards. A primary standard is a reagent that we can use to dispense an accurately known amount of analyte. For example, a 0.1250-g sample of K 2Cr 2O 7 contains \(4.249 \times 10^\). A primary standard must have a known stoichiometry, a known purity (or assay), and it must be stable during long-term storage. Because it is difficult to establishing accurately the degree of hydration, even after drying, a hydrated reagent usually is not a primary standard. Reagents that do not meet these criteria are secondary standards. The concentration of a secondary standard is determined relative to a primary standard. Lists of acceptable primary standards are available (see, for instance, Smi...