The Acid-Dissociation Constants of Phosphoric Acid (H₂PO₃)are K_al = 7

question 21

Multiple Choice

The acid-dissociation constants of phosphoric acid (H₂PO₃) are K_al = 7.5 × 10^-3, K_a2 = 6.2 × 10^-8, and K_a3 = 4.2 × 10^-13 at 25.0°C. What is the pH of a 2.5 M aqueous solution of phosphoric acid?

• A)1.82
• B)0.40
• C)2.51
• D)0.86
• E)0.13

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