Negative of the logarithm

To find appropriate empirical pair potentials from the known protein structures in the Brookhaven Protein Data Bank, it is necessary to calculate densities for the distance distribution of Ga-atoms at given bond distance d and given residue assignments ai,a2- Up to a constant factor that is immaterial for subsequent structure determination by global optimization, the potentials then ciiiergo as the negative logarithm of the densities. Since... 

Acidity is defined in terms of the pH scale, where pH is the negative logarithm of the hydrogen ion [H ] concentration. 

PK. — the negative logarithm of the equilibrium constant for acids or bases. This parameter is an indicator of the strength of an acid or base. Strong acids, such as H2SO4, and HCl, have low pK s (i.e., -1.0) while strong bases such as KOH and NaOH, have pK s close to 14.0. Weak acids and weak bases fall in the intermediate range. 

Confining attention to the case in which the concentrations of the acid and its salt are equal, i.e. of a half-neutralised acid then pH = pKa. Thus the pH of a half-neutralised solution of a weak acid is equal to the negative logarithm of the dissociation constant of the acid. For acetic (ethanoic) acid, Ka = 1.75 x 10 5 mol L 1, pKfl = 4.76 a half-neutralised solution of, say 0.1M acetic acid will have a pH of 4.76. If we add a small concentration of H + ions to such a solution, the former will combine with acetate ions to form undissociated acetic acid ... 

Figurel. Equilibrium potential / pH diagram of the Pb/H20 system at 25 °C, according to Pourbaix [10], but simplified for a = lmol L 1. The pH value is used to express the acidity of the solution. Its definition is pH = -log( H.) pH stands for the negative logarithm of the activity of the H+ ions.

Step 5 If acid is in excess, take the negative logarithm of the H3Oa molarity to find the pH. If base is in excess, find the pOH, and then convert pOH into pH by using the relation pH + pOH = p Kw. 

The negative logarithm of the concentration of antagonist that causes a concentration ratio of x is commonly denoted by pA(. This term was introduced by H. O. Schild as an empirical measure of the activity of an antagonist. The value most often quoted is pA2, where... 

Kf is the stability constant which is the negative logarithm of the dissociation constant, Ki. The dissociation constant is the product of the concentrations of the dissociated ions divided by the concentration of the parent molecule. 

In 1909, Danish biochemist Soren Sorenson first introduced the pH concept. pH is defined by the negative logarithm of the hydrogen ion activity ... 

Consider how a weak electrolyte is distributed across the gastric mucosa between plasma (pH 7.4) and gastric fluid (pH 1.0). In each compartment, the Henderson-Hasselbalch equation gives the ratio of acid-base concentrations. The negative logarithm of the acid dissociation constant is designated here by the symbol pAa rather than the more precisely correct pK1. 

This has been defined by Ken Raymond as the negative logarithm of the concentration of the free or uncom-... 

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