Question

Massa CH3COONa ( Mr=82 ) yang terlarut dalam 10 mL larutan CH3COONa pH= 9 adalah...

tolong dibantu ya

Answer 1

Ph = 9 , pOH = 5
M = 10^-5
M= n/v
n= M x v
   =10^-5 . 0,01 L
   =10^-7 mol
mol = massa / Mr
massa = mol x Mr
         = 10^-7 x 82
        =0,0000082 gram

Answer 2

PH = 9 
pOH = 14 -9 = 5
[OH⁻] = 10⁻⁵

V = 10 mL = 10⁻² L
gunakan rumus hidrolisis
[OH⁻]   = √ ( Kw/Ka) x M
           =√ ( Kw/Ka) x (m / Mr x V)
 10⁻⁵    = √ ( 10⁻¹⁴/ 1,8 x 10⁻⁵) x ( m / (82 x 10⁻²))
(10⁻⁵)²  = (√ ( 10⁻¹⁴/ 1,8 x 10⁻⁵) x ( m / 0,82))²
10⁻¹⁰    = 10⁻¹⁴/ 1,8 x 10⁻⁵ x ( m/0,82)
      m  = (10⁻¹⁰ x 1,8 x 10⁻⁵ x 0,82) / 10⁻¹⁴
           = 1,476 x 10 ⁻¹⁵ / 10⁻¹⁴
           = 1,476 x 10⁻¹ gram

ada pendapat lain, saya sedikit gak yakin..