Answer:
pKa of the acid is 3.6
Explanation:
When a weak acid, HX, reacts with NaOH, the conjugate base, X⁻, is produced:
HX + NaOH → X⁻ + Na⁺ + H₂O
At the half neutralized solution, [HX] = [X-]
Based on Henderson-Hasselbalch equation:
pH = pKa + log [ X⁻] / [HX]
<em>Where pH is the pH of the buffer = 3.6</em>
<em>pKa is the pka of the solution</em>
<em>And as [ X⁻] = [HX], [ X⁻] / [HX] = 1</em>
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Replacing:
3.6 = pKa + log 1
3.6 = pKa + 0
<h3>pKa of the acid is 3.6</h3>
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Ans: Calcium sulfate.
K2SO4 (aq) + Ca(NO3)2 (aq) ⇒ 2KNO3 (aq) + CaSO4 (s)