Question: What is the pH of a 0.01 M solution of phosphoric acid (H3PO4)?
Options:
1.0
2.0
3.0
4.0
Correct Answer: 2.0
Solution:
H3PO4 is a triprotic acid; for a dilute solution, the first dissociation dominates, giving pH ≈ 2.
What is the pH of a 0.01 M solution of phosphoric acid (H3PO4)?
Practice Questions
Q1
What is the pH of a 0.01 M solution of phosphoric acid (H3PO4)?
1.0
2.0
3.0
4.0
Questions & Step-by-Step Solutions
What is the pH of a 0.01 M solution of phosphoric acid (H3PO4)?
Step 1: Understand that phosphoric acid (H3PO4) is a triprotic acid, meaning it can donate three protons (H+ ions) in solution.
Step 2: For a very dilute solution like 0.01 M, the first dissociation (H3PO4 → H+ + H2PO4-) is the most significant.
Step 3: Calculate the concentration of H+ ions from the first dissociation. In a 0.01 M solution, we can assume that nearly all of the acid dissociates to give approximately 0.01 M of H+ ions.
Step 4: Use the formula for pH, which is pH = -log[H+]. Here, [H+] is approximately 0.01 M.
Step 5: Calculate pH: pH = -log(0.01) = 2.
No concepts available.
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