Chemistry - Ionic Equilibrium Question with Solution | TestHub

ChemistryIonic EquilibriumpH of Strong and Weak Acids and BasesMedium2 minQB

ChemistryMediummultiple choice

H₂A is a weak diprotic acid. If the pH of a $0.1 M H_{2} A$ solution is 3, and the concentration of $A^{2 -}$ is $1 0^{- 12}$ at 25°C, select the correct statement(s):

Options:(select one or more)

Answer:

A, C

Solution:

$H_{2} A ⇌ H^{+} + HA^{-}$

At eq. $C - x x + y x - y$

$HA^{-} ⇌ H^{+} + A^{2 -}$

At eq. $x - y x + y y$

Because $y$ is very small,

$so x + y ≃ x Ka_{2} = y = 1 0^{- 12} pKa_{2} = 12 ∴ Ka_{1} = \frac{x ^{2}}{C - x} pH = \frac{1}{2} [pKa_{1} - lo g C] 3 = \frac{1}{2} [pKa_{1} + 1] pKa_{1} = 5$

Stream:JEESubject:ChemistryTopic:Ionic EquilibriumSubtopic:pH of Strong and Weak Acids and Bases

⏱ 2mℹ️ Source: QB

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