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Suatu larutan basa lemah LOH 0,02 M mempunyai pH s...

Suatu larutan basa lemah LOH 0,02 M mempunyai pH sebesar 11. Tentukan pH larutan yang terjadi jika ke dalam 10 mL larutan 0,01 M LOH dimasukkan 10 mL larutan 0,01 M HI! 

Jawaban:

Langkah pertama mencari nilai Kb dari LOH

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row pH equals cell 14 minus sign pOH end cell row 11 equals cell 14 minus sign pOH end cell row pOH equals 3 row cell open square brackets O H to the power of minus sign close square brackets end cell equals cell 10 to the power of negative sign 3 end exponent end cell row cell open square brackets O H to the power of minus sign close square brackets end cell equals cell square root of K subscript b cross times open square brackets LOH close square brackets end root end cell row cell 10 to the power of negative sign 3 end exponent end cell equals cell square root of K subscript b cross times 0 comma 02 end root end cell row cell K subscript b end cell equals cell fraction numerator open parentheses 10 to the power of negative sign 3 end exponent close parentheses squared over denominator 2 cross times 10 to the power of negative sign 2 end exponent end fraction end cell row blank equals cell 5 cross times 10 to the power of negative sign 5 end exponent end cell end table end style 

Langkah berikutnya tuliskan reaksi antara LOH dengan HI

 

dari reaksi tersebut didapatkan garam LI yang terhidrolsis parsial dan bersifat asam, maka pH larutan garam LI dapat dihitung dengan persamaan berikut:

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell H to the power of plus sign end cell equals cell square root of K subscript w over K subscript b cross times L to the power of plus sign end root end cell row blank equals cell square root of fraction numerator 10 to the power of negative sign 14 end exponent over denominator 5 cross times 10 to the power of negative sign 5 end exponent end fraction cross times 5 cross times 10 to the power of negative sign 3 end exponent end root end cell row blank equals cell 10 to the power of negative sign 6 end exponent space M end cell row cell pH space end cell equals cell space minus sign log open parentheses 10 to the power of negative sign 6 end exponent close parentheses end cell row blank equals 6 end table end style 

Jadi, pH larutan yang berbentuk adalah 6

 

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