Question

At what pH will phenobarbital begin to separate from its solution? Phenobarbital is a weak acid.
Initial conc. 0.0393M
Ionized conc. 0.0043M
Ka 3.9x10^-8

ROUND OFF TO 2 DECIMAL PLACES.

Answer 1

Solution.

$3.9\times 10^{-8} = \frac{x^2}{(0.0393-x)}$

$x = 3.91 \times 10^{-5}$

$pH = -lg[H^+] = 4.41$

Answer:

4.41