Question

Use Table 18.a or Apendix C to calculate the percent dissociation of 0.071 M CH₃COOH.

Answer 1

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Use Table 18.a or Apendix C to calculate the percent dissociation of 0.064 M CH₃COOH.

I'll use 1.8x10^-5 as the Ka of acetic acid. (Your text may use 1.75x10^-5 or another value close to this).

HA <--> H^+1 + A^-1
Ka = [H+][A-]/[HA]
Let [H+] = X (and [A-] also equals X)

For 0.064 M acetic acid-
1.8x10^-5 = X^2 / (0.064 - X)
The denominator will be 0.064 because X << 0.064
1.8x10^-5 = X^2 / 0.064
X = 1*10^-6
1*10^-6 / 0.064 = 1.5*10^5 (0.0015% dissociated)