Table of equilibrium concentrations of hydronium, acetate, and acetic acid in th
ID: 546859 • Letter: T
Question
Table of equilibrium concentrations of hydronium, acetate, and acetic acid in the 0 g, 0.5 g, and 2.0 g (0.5 g+ 1.5 g) samples of sodium acetate in 0.100 M acetic acid. (Use your pH to determine the [H30"], then use that value to determine the [C2H302] and [HC2H302] Don't forget to include the added amount of C2H302 and the amount from the dissociation of acetic acid.)(5 pts) o Total Conc. NaC2H302 PH Total Conc. Acid 0.100 M 0.100 M 0.100 M H30'] [C2H302] (M) [HC2H302l (M) 0.5 . 16 1.5 What is the average value for the acid dissociation constant for acetic acid as calculated from the pH of the various acetic acid/sodium acetate solutions? (1 pt) oExplanation / Answer
pH = 4.45
[H3O+] = 10-pH
[H3O+] = 10-4.45
[H3O+] = 3.55 x 10-5 M
For sodium acetate buffer, pKa = 4.76
pH = pKa + log ( [CH3COO-] / [CH3COOH] )
4.45 = 4.76 + log ( [CH3COO-] / [CH3COOH] )
log ( [CH3COO-] / [CH3COOH] ) = -0.31
[CH3COO-] / [CH3COOH] = 0.489
[CH3COO-] = 0.489 x 0.1 = 0.0489 M
[CH3COO-] added = 0.5 / (59x100/1000) = 0.0847 M
[CH3COOH] added = 2 / (60x100/1000) = 0.333 M
Final Concentration of [CH3COO-] = 0.0489 + 0.0847 = 0.1336 M
Final Concentration of [CH3COOH] = 0.1 + 0.3333 = 0.4333 M
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