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In chemistry, acid value (AV, acid number, neutralization number or acidity) is a number used to quantify the acidity of a given chemical substance.It is the quantity of base (usually potassium hydroxide (KOH)), expressed as milligrams of KOH required to neutralize the acidic constituents in 1 gram of a sample.
The pH range is commonly given as zero to 14, but a pH value can be less than 0 for very concentrated strong acids or greater than 14 for very concentrated strong bases. [2] The pH scale is traceable to a set of standard solutions whose pH is established by international agreement. [3]
Pauling's second rule is that the value of the first pK a for acids of the formula XO m (OH) n depends primarily on the number of oxo groups m, and is approximately independent of the number of hydroxy groups n, and also of the central atom X. Approximate values of pK a are 8 for m = 0, 2 for m = 1, −3 for m = 2 and < −10 for m = 3. [28]
In and of themselves, pH indicators are usually weak acids or weak bases. The general reaction scheme of acidic pH indicators in aqueous solutions can be formulated as: HInd (aq) + H 2 O (l) ⇌ H 3 O + (aq) + Ind − (aq) where, "HInd" is the acidic form and "Ind −" is the conjugate base of the indicator. Vice versa for basic pH indicators ...
Molar concentration or molarity is most commonly expressed in units of moles of solute per litre of solution. [1] For use in broader applications, it is defined as amount of substance of solute per unit volume of solution, or per unit volume available to the species, represented by lowercase c {\displaystyle c} : [ 2 ]
Where HV is the hydroxyl value; V B is the amount (ml) potassium hydroxide solution required for the titration of the blank; V acet is the amount (ml) of potassium hydroxide solution required for the titration of the acetylated sample; W acet is the weight of the sample (in grams) used for acetylation; N is the normality of the titrant; 56.1 is ...
Acid strength is the tendency of an acid, symbolised by the chemical formula, to dissociate into a proton, +, and an anion, .The dissociation or ionization of a strong acid in solution is effectively complete, except in its most concentrated solutions.
A buffer solution is a solution where the pH does not change significantly on dilution or if an acid or base is added at constant temperature. [1] Its pH changes very little when a small amount of strong acid or base is added to it. Buffer solutions are used as a means of keeping pH at a nearly constant value in a wide variety of chemical ...