Question

${\gamma }_m$ acetic acid increases with increasing dilution. What will be the ${\gamma }_m$ of acetic acid solution when sodium hydroxide is added :

• A. Increases
• B. Decreases
• C. Remains same
• D. First decreases and then increases

Answer 1

The correct option is A Increases

Molar conductance (${\gamma }_m$) is the conductance of all ions present in one mole of electrolyte in the solution. Molar conductance of acetic acid increases with increase in dilution. At dilution, degree of ionization (dissociation) increases since volume increases and it leads to the increase in molar conductance of the solution. When acetic acid is added to sodium hydroxide, the molar conductance of acetic acid increases since sodium acetate (salt) will be produced from the acid-base reaction an it leads to the further increase in the degree of dissociation. The reaction can be written as,

$C{H}_{3}COOH+NaOH\to C{H}_{3}CO{O}^{-}N{a}^{+}+H_{2}O$

Thus, molar conductance of aceticacid increase when sodium hydroxide is added.

Thus, option-A is correct.