What is the percent ionization for a weak acid HX that is 0.40 M? Ka = 4.0 × 10 −7 . 1. 0.10% 2. 2.0% 3. 0.050?

What is the percent ionization for a weak acid HX that is 0.40 M? Ka = 4.0 × 10^−7.

1. 0.10%

2. 2.0%

3. 0.050%

4. 0.00020%

5. 0.020%

1 Answer

  • Equation:

    Ka = [H+]*[X-] / [HX]

    [H+] = [OH-] and [HX] = 0.40M

    4.0*10^-7 = [H+]² / 0.4

    [H+]² = (4.0*10^-7)*0.4

    [H+]² = 1.6*10^-7

    [H+] = 4*10^-4

    % dissociation = (4*10^*4)/ 0.40*100 = 0.1% dissociated.

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