pH

$pH$ – measure of hydrogen ion concentration

$pH$ = [ $H^+$ ]

scale: acidic neutral basic

$pH$ : 1 ———————- 7 ———————— 14

Examples: HCL Water NaOH

hydronium ion → $H_{3}O^{+}$

$pH$ is determined by the amount of $H_{3}O^{+}$ relative to $OH^{-}$

high [ $H_{3}O^{+}$ ] means it’s more acidic

$pH=-log[$H_{3}O^{+}$]$

Concentration must be in $\frac{mol}{L}$ → M, molarity

Calculate the $pH$ of a solution with [ $H_{3}O^{+}$ ] = $3.8 \times 10^{-3} \hspace{0.1cm} mol/L$

$pH=-log[$H_{3}O^{+}$]$

$pH=-log[3.8 \times 10^{-3} \hspace{0.1cm} mol/L]$

$pH=2.4$ → acidic