After Adding 25

question 54

Multiple Choice

After adding 25.0 mL of 0.100 M NaOH to 100.0 mL of 0.100 M weak acid (HA) , the pH is found to be 5.90. Determine the value of K_a for the acid HA.

• A) 4.2 × 10^-7
• B) 3.5 × 10^-9
• C) 1.6 × 10^-11
• D) 2.1 × 10^-5
• E) none of these

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