Definition of $pH$ and $pOH$
Tutorial 3
Ionization of water, pH and pOH definition
$ [\; ] $ Denotes molarity = concentration in mole per liter
$ H_3O^+ $ is the hydronium ion
$ OH^- $ is the hydroxide ion
Ionization of water
$ 2H_2O $ $ \leftrightarrows $ $H_3O^+ $ $ + $ $OH^- $
$ [H_3O^+] [OH^-] $ $ = $ $ 10^{-14} $ $ = $ $ K_e $
This relationship is valid both for pure water and for any dilute aqueous solution STP
Definition of pH
$pH$ $=$ $-log[H_3O^+]$
so:
$[H_3O^+]$ $=$ $10^{-pH}$
Definition of pOH
$pOH$ $=$ $-log[OH^-]$
so:
$[OH^-]$ $=$ $10^{-pOH}$
Relation between pH and pOH
$pOH$ $+$ $pOH$ $=$ $14$
This relationship holds for both pure water and any dilute aqueous solution STP
Which of the following statements is correct?
a) The greater [H+], the greater the pH
B) The smaller the pH, the smaller [OH-]
C) The larger the pOH, the smaller [H+]
D) The smaller the [H3O+], the smaller [H+]
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Complete please this question before moving on to the next one!
b) is correct:
The smaller the pH, the more $ [OH^-] $ is small