Oxalic acid is diprotic with p K _al = 1.23 and p K _a2 = 4.19. Estimate the pH of a solution of sodium hydrogen oxalate.

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Sodium hydrogen oxalate is the salt of a weak acid (oxalic acid) and a strong base (sodium hydroxide). In water, it partially dissociates to form oxalate ion and hydronium ion. The pH of the solution can be estimated using the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where pKa is the dissociation constant of the acid, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the acid. Since sodium hydrogen oxalate is the conjugate base of the first dissociation step of oxalic acid, we use pKa1 = 1.23. However, because the solution essentially consists of the conjugate base and its corresponding acid (oxalic acid and hydrogen oxalate), the pH will be closer to the second pKa, which is 4.19, but slightly lower because it's the conjugate base of the second dissociation. Therefore, the pH is estimated to be around 3, which is closer to the second pKa but slightly lower, reflecting the acidic nature of the solution.

Oxalic Acid Is Diprotic with P K al = 1

Oxalic Acid Is Diprotic with P K _al = 1