1. Tardigrade
  2. Question
  3. Chemistry
  4. pK a 1, pK a 2 and pK a 3 of H 3 PO 4 are respectively 4,8,12 respectively TK. To a 50 ml solution of 0.1 M Na 3 PO 4, 50 ml 0.2 M HCl is added. Find the pH of the mixture obtained at TK.

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Q. $pK _{ a _{1}}, pK _{ a _{2}}$ and $pK _{ a _{3}}$ of $H _{3} PO _{4}$ are respectively $4,8,12$ respectively TK. To a $50 \,ml$ solution of $0.1 \,M\, Na _{3} PO _{4}$, $50\, ml \,0.2\, M \,HCl$ is added. Find the $pH$ of the mixture obtained at TK.

Equilibrium

Solution:

$PO _{4}^{3-}+2 H ^{+} {\longrightarrow} H _{2} PO _{4}^{-}$
$\therefore pH =\frac{ pK _{ a _{1}}+ pK _{ a _{2}}}{2}=6$