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A 10.00 mL portion of a solution of a weak monoprotic (one H^+) acid HA was titr

ID: 495430 • Letter: A

Question

A 10.00 mL portion of a solution of a weak monoprotic (one H^+) acid HA was titrated with 0.1894 M NaOH. The results of the titration are tabulated below. (a) Write the balanced chemical equation for the titration reaction. (b) Plot the pH titration curve from the tabulated data. (c) From the titration curve, determine the end the titration. (d) Use the endpoint volume to calculate the number of moles NaOH used in the titration. (e) Use the number of moles of NaOH and the balanced chemical equation to calculate the number of that reacted during the titration. (f) Use number of moles of HA and the volume of the original HA solution (10.00 mL) to calculate the original concentration of HA in the analyze.

Explanation / Answer

0.1 M acetic acid

b. Dissociation

CH3COOH + H2O <==> CH3COO- + H3O+

Ka = [CH3COO-][H3O+]/[CH3COOH]

c. let x amount of acid has dissociated

Ka = 1.8 x 10^-5

1.8 x 10^-5 = x^2/0.1

x = [H+] = 1.34 x 10^-3 M

d. pH = -log[H+]

         = -log(1.34 x 10^-3)

         = 2.87