What is the pH at 25 degrees C of a 0.0010 M solution of barium hydroxide, Ba(OH)2, assuming complete dissociation? (log 2 = 0.30)
Answer and explanation
Correct answer: C. 11.30
- Step 1: Ba(OH)2 releases two hydroxide ions per formula unit, so [OH-] = 2 x 0.0010 = 0.0020 M. Step 2. pOH = -log(2.0 x 10^-3) = 3 - 0.30 = 2.70. Step 3. pH = 14.00 - 2.70 = 11.30. Answer: 11.30. Why not the others: 11.00 ignores the second hydroxide, 10.70 halves the concentration instead of doubling it, and 2.70 is the pOH, not the pH.
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