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Pertanyaan

Satu liter larutan NaOH dielektrolisis dengan arus sebesar 965 coulomb, tentukan pH larutan yang terjadi

2 Jawaban

  • katoda : 2H2O + 4e → H2 + 4OH^-
    anoda: 4OH^- → 2H2O + O2 + 4e

    jumlah mol elektron :
    n = 965/96500
    n = 0.01 mol

    mol OH^- = mol elektron = 0.01 mol
    [OH^-] = n/V
    [OH^-] = 0.01/2

    pH = 14 - pOH
    pH = 14 - (- log (0.01/2))
    pH = 14 + log (5*10^-3)
    pH = 14 - 3 + log 5
    pH = 11 + log 5
  • reaksi elektrolisis
    katoda : 2H₂O + 4e⁻ → H₂ + 4OH⁻
    anoda: 4OH⁻ → 2H₂O + O2 + 4e⁻

    ev = 1
    Q = 965 coloumb
    mol elektron = Q/96500 = 965/96500 = 0.01 mol
    mol OH⁻ = mol elektron
                  = 0.01 mol
    [OH⁻] = mol/volume
              = 0.01/1 = 0.01 Molar
    pOH = -log [OH⁻]
            = - log 0.01
            = 2
    pH = 14 - pOH
         = 14 - 2 = 12

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