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Relation between pH and pOH. Red represents the acidic region. Blue represents the basic region. 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.
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 ...
Hypophosphoric acid can be prepared by the reaction of red phosphorus with sodium chlorite at room temperature. [2]2 P + 2 NaClO 2 + 2 H 2 O → Na 2 H 2 P 2 O 6 + 2 HCl. A mixture of hypophosphoric acid, phosphorous acid (H 3 PO 3) and phosphoric acid (H 3 PO 4) is produced when white phosphorus oxidises in air when partially immersed in water.
The isoelectric point (pI, pH(I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH(I). [1] However, pI is also used. [2] For brevity, this article uses pI.
The Henderson–Hasselbalch equation can be used to model these equilibria. It is important to maintain this pH of 7.4 to ensure enzymes are able to work optimally. [10] Life threatening Acidosis (a low blood pH resulting in nausea, headaches, and even coma, and convulsions) is due to a lack of functioning of enzymes at a low pH. [10]
In particular, the pH of a solution can be predicted when the analytical concentration and pK a values of all acids and bases are known; conversely, it is possible to calculate the equilibrium concentration of the acids and bases in solution when the pH is known. These calculations find application in many different areas of chemistry, biology ...
The main factor affecting the formal (or apparent) reduction potentials ′ in biochemical or biological processes is the pH. To determine approximate values of formal reduction potentials, neglecting in a first approach changes in activity coefficients due to ionic strength, the Nernst equation has to be applied taking care to first express ...
A pH of 7 therefore corresponds to a pOH of 7, and a pH of 9 with a pOH of 5. Formally it is preferred to express the ion concentrations in terms of chemical activity, but this hardly affects the value of the pH. Water with excess H 3 O + ions is called acid (pH < 7), and water with excess OH – ions is called alkaline or rather basic (pH > 7).