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McIlvaine buffer is a buffer solution composed of citric acid and disodium hydrogen phosphate, also known as citrate-phosphate buffer. It was introduced in 1921 by the United States agronomist Theodore Clinton McIlvaine (1875–1959) from West Virginia University , and it can be prepared in pH 2.2 to 8 by mixing two stock solutions.
Buffer capacity falls to 33% of the maximum value at pH = pK a ± 1, to 10% at pH = pK a ± 1.5 and to 1% at pH = pK a ± 2. For this reason the most useful range is approximately pK a ± 1. When choosing a buffer for use at a specific pH, it should have a pK a value as close as possible to that pH. [2]
In countries without labeling, it is possible to calculate the pure alcohol mass in a serving from the concentration, density of alcohol, and volume: = For example, a 350 ml (12 US fl oz) glass of beer with an ABV of 5.5% contains 19.25 ml of pure alcohol, which has a density of 0.78945 g/mL (at 20 °C), [ 32 ] and therefore a mass of 15.20 ...
The alcohol content of the spirit can then be measured using a hydrometer and tables of density of alcohol and water mixtures. [3] A second accurate method is the ebulliometer method, which uses the difference between the boiling temperature of pure water and the boiling temperature of the beer being tested.
At relatively low alc/vol, the alcohol percentage by weight is about 4/5 of the alc/vol (e.g., 3.2% ABW is about 4% alc/vol). [25] However, because of the miscibility of alcohol and water, the conversion factor is not constant but rather depends upon the concentration of alcohol. [citation needed]
For example, if there are 10 grams of salt (the solute) dissolved in 1 litre of water (the solvent), this solution has a certain salt concentration . If one adds 1 litre of water to this solution, the salt concentration is reduced. The diluted solution still contains 10 grams of salt (0.171 moles of NaCl).
This Wikipedia page provides a comprehensive list of boiling and freezing points for various solvents.
The P-value only correctly refers to the concentration ratio of a single substance distributed between the octanol and water phases. In the case of a substance that occurs as multiple species, it can therefore be calculated by summing the concentrations of all n species in the octanol phase and the concentrations of all n species in the aqueous ...