Jawabanmu

2014-02-04T18:45:19+07:00
1. pH = 4 = -log [H⁺]
    pH = 4 - log 1 (log 1 sama dengan 0 sehingga jarang digunakan)
     pH = - log 1 x 10⁻⁴
     10⁻⁴ = α M --> M = 10⁻⁴/α --> M = 10⁻⁴/0.005 = 0.02M
     [H⁺] = √Ka x M --> 10⁻⁴ = √Ka x 0.02 --> Ka = (10⁻⁴)² / 0.02 = 5 x 10⁻⁷

2. 500ml NH₄OH (basa lemah) 0.1 M pH = 10
     pH = 14 - pOH --> pOH = 14 - pH --> pOH = 14 - 10 = 4
     pOH = -log[OH⁻] = 4 - log 1 = -log 10⁻⁴ --> [OH-] = 10⁻⁴
     [OH-] = α M = α 0.1 --> α = 10⁻⁴/0.1 = 10⁻³ = 1/1000

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