The ka value for acetic acid, ch3cooh(aq), is 1.8ã 10â5 m. calculate the ph of a 1.40 m acetic acid solution.

1) Equlibrium reaction

CH3COOH (aq) = CH3COO(-) (aq) + H(+) (aq)

2) Equilibrium constant

Keq = Ka = [CH3COO-] [H+] / [CH3COOH]

3) Equilibrium concentrations

                  CH3COOH      CH3COO-     H+

start               1.40                  0              0
react                  x                   0              0
produced           0                   x              x

equilibrium     1.40 - x            x               x

=> Ka = x * x / (1.40 - x)

Approximation: given that Ka is very small x <<< 1,40 and 1.40 - x  ≈ 1.40

=> Ka ≈ x^2 / 1.40

=> x^2 ≈ 1.40Ka = 1.40 * 1.8 * 10^ - 5 = 2.52 * 10^-5

=> x ≈ √(2.52 * 10^-5) ≈ 5.02 * 10^ -3 M

4) pH = log 1 / [H+]

[H+] = x = 5.02 * 10^-3M

=> pH ≈ log (1 / 5.02 * 10^-3) ≈ 2.3

2.3

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Non metal is an element or substance that is not a metal metal is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivitymetalloid is an element (e.g., germanium or silicon) whose properties are intermediate between those of metals and solid nonmetals. they are electrical semiconductors.