hi all. I am studying on the acid/base calculations in chem. test is next week a

Question

hi all. I am studying on the acid/base calculations in chem. test is next week and studying some problems in book. if possible show steps. thank u :)

Calulak the pH afa a.35 M aqe ous Soluhan of H6N+)( hydroxy lamme) The Kb of hydroxy larnine) s 1.1x 10 841 q.797 5.59? Calculate, the Concentration of hydroxdL on in a o.0So M Solution ot anilre The base diss ociation constont,k The Base. dissociatim Constant ' kb of (CH3)3 is Lx10- at S. Deteemine in 1T Solution of CCHs2N 1ox10-6? 99x2? 0.6610 what is the pEl of a 0.620M HClo Solutin? 922 7 y.617 9.227

Explanation / Answer

1)

concentration = 0.35 M

Kb = 1.1 x 10^-8

[OH-] = sqrt (Kb x C)

          = sqrt (1.1 x 10^-8 x 0.35)

          = 6.2 x 10^-5

pOH = 4.21

pH = 9.79

2)

concentration = 0.05 M

C6H5NH2 + H2O ----------------> C6H5NH3+ + OH-

0.05                                                    0                 0

0.05 - x                                               x                  x

Kb = x^2 / 0.05 - x

4.3 x 10^-10 = x^2 / 0.05 - x

x = 4.6 x 10^-6

[OH-] = 4.6 x 10^-6 M

3)

(CH3)3N + H2O   ------------------> (CH3)3NH+ + OH-

1.6 x 10^-2                                                0                0

1.6 x 10^-2 - x                                           x                 x

Kb = x^2 / 1.6 x 10^-2 - x

6.4 x 10^-5 = x^2 / 1.6 x 10^-2 - x

x = 9.8 x 10^-4

[OH-] = 9.8 x 10^-4 M

[H+] = 9.9 x 10^-12

4)

[H+] = sqrt (Ka x C) = sqrt (3 x 10^-8 x 0.020)

        = 2.45 x 10^-5 M

pH = -log [H+] = -log(2.45)

      = 4.61

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