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% IONIZATION. 1.) What is the % ionization of a 0.010 M HCOOH, formic acid, solution? (K a = 1.9 x 10 -4 ) HCOOH H + + HCOO - I 0.010 0 0 C -x +x +x E 0.010 – x x x Ka = x 2 = 1.9 x 10 -4 0.010 - x. -x. x 2 = 1.9 x 10 -6 x = 1.4 x 10 -3
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% IONIZATION • 1.) What is the % ionization of a 0.010 M HCOOH, formic acid, solution? (Ka = 1.9 x 10-4) HCOOH H+ + HCOO- I 0.010 0 0 C -x +x +x E 0.010 – x x x Ka = x2 = 1.9 x 10-4 0.010 - x -x
x2 = 1.9 x 10-6 • x = 1.4 x 10-3 • %Ion = x/starting acid x 100 • %Ion = 1.4 x 10-3 / 0.010 x 100 = 14% • 2.) What is the pH of #1? pH = -log [H+]
(.010)(.184)=.00184 • pH = -log (1.4 x 10-3) • pH = 2.85 • 3.) What is the Ka of a 0.010 M solution of HF which is 18.4% ionized? • HF H+ + F- I 0.010 0 0 C -.00184 +.00184 +.00184 E .00816 0.00184 0.00184
Ka = [H+][F-] [HF] Ka = (0.00184)2 = 4.15 x 10-4 0.00816 4.) What is the pH of #3? pH = -log [H+] = -log (0.00184) = 2.74