Jawabanmu

2014-07-21T10:33:12+07:00
Ca(OH)₂ --> basa 
pOH = 14 - (12+log 5)
            2 - log 5
pOH = - log M OH⁻ val
- log 5 x 10⁻² = - log M 2
5 x 10⁻² =M
    2
2,5 x 10⁻² = M

M = gram1000
        Mr        ml
2,5 x 10⁻² = gram1000
                  74       500
185 x 10⁻² = gram
      2
0,925 = gram

Jawaban paling cerdas!
2014-07-21T10:35:49+07:00
Diketahui : v = 500 ml = 0,5 L
                   ph= 12+ log 5
                   Mr Ca(OH)2 = (40 + (17.2)
                                          = 40 + 34 = 74
ditanya : m?

jawab

pKw = pH + pOH
14 = (12 + log 5) + pOH
pOH = 2- log 5

pOH = - log [ OH-]
2- log 5 = - log [OH-]
[OH-] = 5 x 10^-2

[OH-] = M x valensi basa
[5 x 10^-2] = M x 2
M = 0,025

M = n/V
0,025 = n/ 0,5
n = 0,0125
n = m/Mr
0,0125 = m/74
m = 0,0125 x 74
m = 0,925 gr

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