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Express each concentration value as the ratio c/c 0, where c 0 is the concentration in a [hypothetical] standard state, with a numerical value of 1, by definition. [19] Express the concentrations on the mole fraction scale. Since mole fraction has no dimension, the quotient of concentrations will, by definition, be a pure number.
If the concentration of a sulfuric acid solution is c(H 2 SO 4) = 1 mol/L, then its normality is 2 N. It can also be called a "2 normal" solution. It can also be called a "2 normal" solution. Similarly, for a solution with c (H 3 PO 4 ) = 1 mol/L, the normality is 3 N because phosphoric acid contains 3 acidic H atoms.
The concentration of water, [H 2 O], is omitted by convention, which means that the value of K w differs from the value of K eq that would be computed using that concentration. The value of K w varies with temperature, as shown in the table below. This variation must be taken into account when making precise measurements of quantities such as pH.
A weak base will have a higher H + concentration than a stronger base because it is less completely protonated than a stronger base and, therefore, more hydrogen ions remain in its solution. 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 ...
When the acidic medium in question is a dilute aqueous solution, the is approximately equal to the pH value, which is a negative logarithm of the concentration of aqueous + in solution. The pH of a simple solution of an acid in water is determined by both K a {\displaystyle K_{{\ce {a}}}} and the acid concentration.
The converse is true in a basic medium. For example, Naproxen is a non-steroidal anti-inflammatory drug that is a weak acid (its pKa value is 5.0). The gastric juice has a pH of 2.0. It is a three-fold difference (due to log scale) between its pH and its pKa; therefore there is a 1000× difference between the charged and uncharged concentrations.
The apparent dimension of this K value is concentration 1−p−q; this may be written as M (1−p−q) or mM (1−p−q), where the symbol M signifies a molar concentration (1M = 1 mol dm −3). The apparent dimension of a dissociation constant is the reciprocal of the apparent dimension of the corresponding association constant , and vice versa .
The value H 0 = -12 for pure sulfuric acid must not be interpreted as pH = −12 (which would imply an impossibly high H 3 O + concentration of 10 +12 mol/L in ideal solution). Instead it means that the acid species present (H 3 SO 4 +) has a protonating ability equivalent to H 3 O + at a fictitious (ideal) concentration of 10 12 mol/L, as ...