Question

The charge balance equation of species in $0.100\, M$ acetic acid solution is given by

• A. $ [H^{+}]=[OH^{-}]$
• B. $\left[ H ^{+}\right]=\left[ CH _{3} COO ^{-}\right]$
• C. $\left[ H ^{+}\right]=\left[ OH ^{-}\right]+\left[ CH _{3} COO ^{-}\right]$
• D. $2\left[ H ^{+}\right]=\left[ OH ^{-}\right]+\left[ CH _{3} COO ^{-}\right]$

Answer 1

Answer: (D)

$CH _{3} COOH \rightleftharpoons CH _{3} COO ^{-}+ H ^{+}$
${\left[ CH _{3} COO ^{-}\right]=\left[ H ^{+}\right]}$ ...(i)
$H _{2} O \rightleftharpoons H ^{+}+ OH ^{-}$
${\left[ H ^{+}\right]=\left[ OH ^{-}\right]}$ ...(ii)
From Eq. (i) and (ii), we get
$\left[ H ^{+}\right]+\left[ H ^{+}\right] =\left[ CH _{3} COO ^{-}\right]+\left[ OH ^{-}\right]$
$2\left[ H ^{+}\right] =\left[ CH _{3} COO ^{-}\right]+\left[ OH ^{-}\right]$