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Boric acid is a weak acid, with pK a (the pH at which buffering is strongest because the free acid and borate ion are in equal concentrations) of 9.24 in pure water at 25 °C. But apparent p K a is substantially lower in swimming pool or ocean waters because of interactions with various other molecules in solution.
Borax is also easily converted to boric acid and other borates, which have many applications. Its reaction with hydrochloric acid to form boric acid is: Na 2 B 4 O 7 ·10H 2 O + 2 HCl → 4 H 3 BO 3 + 2 NaCl + 5 H 2 O. Borax is sufficiently stable to find use as a primary standard for acid-base titrimetry. [17]: p.316
The following chart shows the solubility of various ionic compounds in water at 1 atm pressure and room temperature (approx. 25 °C, 298.15 K). "Soluble" means the ionic compound doesn't precipitate, while "slightly soluble" and "insoluble" mean that a solid will precipitate; "slightly soluble" compounds like calcium sulfate may require heat to precipitate.
The tables below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at one atmosphere pressure. Units of solubility are given in grams of substance per 100 millilitres of water (g/100 ml), unless shown otherwise. The substances are listed in alphabetical order.
In aqueous solution, boric acid B(OH) 3 can act as a weak Brønsted acid, that is, a proton donor, with pK a ~ 9. However, it more often acts as a Lewis acid , accepting an electron pair from a hydroxide ion produced by the water autoprotolysis : [ 11 ]
It is formed by the reaction of boric acid and ethanol in the presence of acid catalyst, where it forms according to the equilibrium reaction: B(OH) 3 + 3 C 2 H 5 OH ⇌ (C 2 H 5 O) 3 B + 3 H 2 O. In order to increase the rate of forward reaction, the formed water must be removed from reaction media by either azeotropic distillation or adsorption.
This page contains tables of azeotrope data for various binary and ternary mixtures of solvents. The data include the composition of a mixture by weight (in binary azeotropes, when only one fraction is given, it is the fraction of the second component), the boiling point (b.p.) of a component, the boiling point of a mixture, and the specific gravity of the mixture.
A dehydrating agent, such as concentrated sulfuric acid is typically added. [1] Borate esters are volatile and can be purified by distillation. This procedure is used for analysis of trace amounts of borate and for analysis of boron in steel. [2] Like all boron compounds, alkyl borates burn with a characteristic green flame.