Map Sapling Learning A student must make a buffer solution with a pH of 1.0. Det

Question

Map Sapling Learning A student must make a buffer solution with a pH of 1.0. Determine which of the acids and conjugate bases listed below are the best options to make a buffer at the specified pH. Weak acids: O propionic acid, Ka 1.34x10 5, 3.00 M O acetic acid, Ka 1.75x10-5, 5.00 M sodium bisulfate monohydrate, Ka 1.20x10-2, 3.00 M O formic acid, Ka 1.77x10-4 2.00 M Conjugate bases: sodium acetate trihydrate, CH3COONa. 3H20 O sodium propionate, CH3CH2COONa O sodium formate, HCOONa O sodium sulfate decahydrate, Na2so4. 10H20 Scroll down to view more. The final volume of buffer solution must be 100.00 mL and the final concentration of the weak acid must be 0.100 M Based on this information, what mass of solid Based on this information, what volume of conjugate base should the student weigh out to acid should the student measure to make

Explanation / Answer

Ka of weak acid = 1.20 x 10^-2

pKa of weak acid = 1.92

pH = pKa + log [salt / acid]

1.0 = 1.92 + log [salt / acid]

[salt / acid] = 0.1202

acid moles = 100 x 0.1 / 1000

                  = 0.01

salt / acid = 0.1202

salt / 0.01 = 0.1202

salt (conjugate base) moles = 0.1202 x 0.01

                  = 1.202 x 10^-3

conjugate base molar mass =322.195 g/mol

mass = moles x molar mass

          = 1.202 x 10^-3 x 322.195

          = 0.387 g

mass of conjugate base = 0.387 g

molarity = moles / volume

0.100 = 0.01 / V

V = 0.1 L

volume of acid = 100 mL

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