Which Acid, in Combination with Its Conjugate Base, Would Be

question 31

Multiple Choice

Which acid, in combination with its conjugate base, would be the best choice to make a buffer of pH = 4.20?

• A) acetic acid (K_a = 1.8 × 10^-5)
• B) benzoic acid (K_a = 6.3 × 10^-5)
• C) formic acid (K_a = 1.8 × 10^-4)
• D) hydrofluoric (K_a = 7.2 × 10^-4)
• E) nitrous acid (K_a = 4.5 × 10^-4)