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The concentration of hydroxide ions can be expressed in terms of pOH, which is close to (14 − pH), [note 3] so the pOH of pure water is also close to 7. Addition of a base to water will reduce the hydrogen cation concentration and therefore increase the hydroxide ion concentration (decrease pH, increase pOH) even if the base does not itself ...
pOH is sometimes used as a measure of the concentration of hydroxide ions, OH −. By definition, pOH is the negative logarithm (to the base 10) of the hydroxide ion concentration (mol/L). pOH values can be derived from pH measurements and vice-versa. The concentration of hydroxide ions in water is related to the concentration of hydrogen ions by
Given its greater H + concentration, the formula yields a lower pH value for the weak base. However, pH of bases is usually calculated in terms of the OH − concentration. This is done because the H + concentration is not a part of the reaction, whereas the OH − concentration is. The pOH is defined as:
C A is the analytical concentration of the acid and C H is the concentration the hydrogen ion that has been added to the solution. The self-dissociation of water is ignored. A quantity in square brackets, [X], represents the concentration of the chemical substance X. It is understood that the symbol H + stands for the hydrated hydronium ion.
The molar concentration of hydronium or H + ions determines a solution's pH according to pH = -log([H 3 O +]/M) where M = mol/L. The concentration of hydroxide ions analogously determines a solution's pOH. The molecules in pure water auto-dissociate into aqueous protons and hydroxide ions in the following equilibrium: H 2 O ⇌ OH − (aq) + H ...
For example, if the concentration of the conjugate base is 10 times greater than the concentration of the acid, their ratio is 10:1, and consequently the pH is pK a + 1 or pK b + 1. Conversely, if a 10-fold excess of the acid occurs with respect to the base, the ratio is 1:10 and the pH is p K a − 1 or p K b − 1.
In order to study gas phase interstellar chemistry, it is convenient to distinguish two types of interstellar clouds: diffuse clouds, with T=30-100 K, and n=10–1000 cm −3, and dense clouds with T=10-30K and density n= 10 4-10 3 cm −3. Ion chemical routes in both dense and diffuse clouds have been established for some works (Hartquist 1990).
Household ammonia ranges in concentration by weight from 5% to 10% ammonia. [9] Because aqueous ammonia is a gas dissolved in water, as the water evaporates from a surface, the gas evaporates also, leaving the surface streak-free. Its most common uses are to clean glass [10], porcelain, and stainless steel. It is good at removing grease and is ...