Jawabanmu

2014-03-23T18:16:22+07:00
PH = 8
pOH = 14-8 = 6
[OH-] = 10^-6

[OH+] = Kb x (mol asam lemah)/(mol basa konjugat)
[OH+] = Kb x (mol NH3) / (mol NH4+)
10*-6 = 10^-5 (0,02M x 0,5L) / (mol NH4+)
(mol NH4+) = 0,1 mol


(NH4)2SO4 --> 2 NH4+ + SO4^3-

mol (NH4)2SO4 = 1/2 mol NH4+ = 1/2 x 0,1 = 0,05 mol
massa (NH4)2SO4 = 0,05 x 132 = 6,6 gram

Maaf kalau ada kesalahan :)
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