What is the pOH of the solution if the pKa value of acid is 4.5 & the concentration of salt and acid is 0.1 molar & 0.001 molar respectively
Correct answer: C. 7.5
- A. 5.5
- B. 6.5
- C. 7.5
- D. None
Explanation
To find the pOH, first use the Henderson-Hasselbalch equation: pH = pKa + log([salt]/[acid]). Given pKa = 4.5, [salt] = 0.1 M, and [acid] = 0.001 M, the pH = 4.5 + log(0.1/0.001) = 4.5 + 2 = 6.5. Since pH + pOH = 14, the pOH = 14 - 6.5 = 7.5. Therefore, the correct answer is option C. Other options represent miscalculations or misunderstanding of the relationship between pH and pOH.
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About Acids, Bases and Salts
Acid and base behaviour is explained through the Bronsted-Lowry transfer of protons and the Lewis donation or acceptance of electron pairs. The topic includes pH, pOH, ionisation and water equilibrium, plus salt formation and hydrolysis, where a salt solution may become acidic, basic or neutral.
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