Problem: The Ka of acetic acid (HC2H3O2) is 1.8 x 10-5. What is the pH at 25.0 °C of an aqueous solution that is 0.100 M in acetic acid?a. -2.87b. +11.13c. -11.13d. +6.61e. +2.87

FREE Expert Solution

(1) Construct an ICE table 

(2) Calculate the [H3O+] using Ka expression

Ka = [CH3COO-][H3O+][CH3COOH]1.8x10-5 = (x2)0.1-x

-x is negligible if HAKa >>500 0.11.8x10-5=5555; hence  -x is negligible

1.8x10-5 = (x2)0.1-xx = 0.1 × 1.8x10-5

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Problem Details

The Ka of acetic acid (HC2H3O2) is 1.8 x 10-5. What is the pH at 25.0 °C of an aqueous solution that is 0.100 M in acetic acid?

a. -2.87
b. +11.13
c. -11.13
d. +6.61
e. +2.87

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