bases are found at 25 °c on the ph scale.
where are bases found on the ph scale?
25 °c
the ph scale is logarithmic and approximates the negative of the base 10 logarithm of the molar concentration (measured in units of moles per liter) of hydrogen ions in a solution. more precisely it is the negative of the base 10 logarithm of the activity of the hydrogen ion. at 25 °c, solutions with a ph less than 7 are acidic and solutions with a ph greater than 7 are basic. the neutral value of the ph depends on the temperature, being lower than 7 if the temperature increases. the ph value can be less than 0 for very strong acids, or greater than 14 for very strong bases.
ph
as part of its operational definition of the ph scale, the iupac defines a series of buffer solutions across a range of ph values (often denoted with nbs or nist designation). these solutions have a relatively low ionic strength (≈0.1) compared to that of seawater (≈0.7), and, as a consequence, are not recommended for use in characterizing the ph of seawater, since the ionic strength differences cause changes in electrode potential. to resolve this problem, an alternative series of buffers based on artificial seawater was developed. this new series resolves the problem of ionic strength differences between samples and the buffers, and the new ph scale is referred to as the 'total scale', often denoted as ph. the total scale was defined using a medium containing sulfate ions. these ions experience protonation, h + so hso, such that the total scale includes the effect of both protons (free hydrogen ions) and hydrogen sulfate ions:
ph