What mass of solid NaCH₃CO₂ (molar mass = 82.0 g/mol)should be added to 1.0 L of 0.50 M CH₃CO₂H to make a buffer with a pH of 7.21? (pK_a of CH₃CO₂H = 7.21) A) 0.0 g B) 1.9 g C) 41 g D) 71 g E) 1.6 $\times$ 10² g

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Quizplus · Accepted Answer

To make a buffer with a pH equal to the pKa, the concentrations of the acid and its conjugate base should be equal. Since the initial concentration of CH₃CO₂H is 0.50 M, we need 0.50 moles of NaCH₃CO₂ in 1.0 L. The mass required is 0.50 moles × 82.0 g/mol = 41 g.

What Mass of Solid NaCH3CO2 (Molar Mass = 82 ×\times× 102 G

What Mass of Solid NaCH₃CO₂ (Molar Mass = 82 $\times$ 10² G