Question

what is the pH value of 10^-6 M HCl is​

Answer 1

$\textsf{\underline {\Large{ Equilibrium}}}$ :

$\textsf{\underline {\large{pH Value}}}$ :

HCl is a strong monobasic acid. Hence, it completely dissociates into $\mathsf{{H} ^{+}}$ and $\mathsf{{Cl} ^{-}}$.

The chemical reaction will be :

➡️ $\boxed{\mathsf{HCl\:{\rightarrow{\:{H} ^{+} \:+\:{Cl} ^{-}}}}}$

Given, Concentration of HCl = $\mathsf{{10} ^{-6} M}$

$\mathsf{{[\:H\:]}^{+}\:=\:[\:HCl\:]\:=\:{10} ^{-6} M}$

Now,

➡️ $\boxed{\mathsf{pH\:=\:-log\:[\:{H}^{+}\:]}}$

$\mathsf{pH\:=\:-\:log{10} ^{-6}}$

$\mathsf{pH\:=\: - \:(-6\:log\:10)}$

$\mathsf{pH\:=\:(6\:log\:10\:)}$

$\boxed{\mathsf{pH\:=\:6}}$

$\textsf{\underline {\large{Terms Related }}}$ :

$\textsf{\underline {pH scale and pH value}}$ : $\mathsf{{H} ^{+}}$ ion concentration in molarity is expressed as a logarithmic scale known as pH scale.

pH may be defined as the negative logarithm of $\mathsf{{H} ^{+}}$ ion ( or $\mathsf{{H} _{3}O}^{+}$ ion) concentration expressed in mol/l.

➡️ $\boxed{\mathsf{pH\:=\:-log\:[\:{H}^{+}\:]}}$

Similarly for $\mathsf{{OH} ^{-}}$ ion,

➡️ $\boxed{\mathsf{pOH\:=\:-log\:[\:{OH}^{-}\:]}}$

➡️ $\boxed{\mathsf{pH\:+\:pOH\:=\:14}}$

⚫[ ] represents active mass or molar concentration of any substance. It's unit is mol/l.

$\textsf{\underline {\large{About Logarithm }}}$ :

⚫$\boxed{\mathsf{log_a\:{m} ^{n} \:=\:n\:log_a\:m}}$

⚫$\boxed{\mathsf{log_a\:mn\:=\:log_a\:m\:+\:log_a\:n}}$

⚫$\boxed{\mathsf{log\:10\:=\:1}}$