A student must prepare 250 mL of an acetic acid–acetate buffer whose pH is within…

CHEMISTRY · Single correct · A Level · Chemistry · Acids and bases · Acids and bases

Problem

A student must prepare 250 mL of an acetic acid–acetate buffer whose pH is within 0.20 units of the pKₐ of acetic acid (4.74). The buffer must be able to neutralize 0.010 mol of added NaOH. Only 1.0 M CH₃COOH and 1.0 M NaCH₃COO stock solutions are available; the remainder of the volume is made up with distilled water. Which set of volumes meets both requirements? (a) 40  mL CH3COOH,  40  mL NaCH3COO,  water to 250  mL40\;\text{mL }\mathrm{CH_3COOH},\;40\;\text{mL }\mathrm{NaCH_3COO},\;\text{water to }250\;\text{mL} (b) 50  mL CH3COOH,  25  mL NaCH3COO,  water to 250  mL50\;\text{mL }\mathrm{CH_3COOH},\;25\;\text{mL }\mathrm{NaCH_3COO},\;\text{water to }250\;\text{mL} (c) 60  mL CH3COOH,  40  mL NaCH3COO,  water to 250  mL60\;\text{mL }\mathrm{CH_3COOH},\;40\;\text{mL }\mathrm{NaCH_3COO},\;\text{water to }250\;\text{mL} (d) 40  mL CH3COOH,  60  mL NaCH3COO,  water to 250  mL40\;\text{mL }\mathrm{CH_3COOH},\;60\;\text{mL }\mathrm{NaCH_3COO},\;\text{water to }250\;\text{mL}

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