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)

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To make a buffer at pH 7.21, we want a weak acid and its conjugate base in roughly equal amounts. The pKa of CH₃CO₂H is given as 7.21, which means that at that pH, half of the CH₃CO₂H will be in its deprotonated form (HCOO-) and half will be in its protonated form (HCOOH). We can use the Henderson-Hasselbalch equation to calculate the ratio of [HCOO-]/[HCOOH] needed to achieve a pH of 7.21: pH = pKa + log([HCOO-]/[HCOOH]) 7.21 = 7.21 + log([HCOO-]/[HCOOH]) log([HCOO-]/[HCOOH]) = 0 [HCOO-]/[HCOOH] = 1 So we want to add equal amounts of HCOOH and HCOO- to the solution. The concentration of CH₃CO₂H is given as 0.50 M in 1.0 L of solution, which means there are 0.50 moles of CH₃CO₂H in the solution. To achieve equal amounts of HCOOH and HCOO-, we need to add an additional 0.50 moles of HCOO-. The molar mass of CH₃CO₂ is given as 82.0 g/mol, so 0.50 moles of CH₃CO₂H would weigh 41 g. Therefore, we need to add 41 g of solid CH₃CO₂ to the solution to make a buffer with a pH of 7.21.

What Mass of Solid NaCH3CO2 (Molar Mass = 82

What Mass of Solid NaCH₃CO₂ (Molar Mass = 82