Suatu basa lemah BOH 0,01 M mempunyai harga pH = 3 - log 2; hitunglah harga Kb basa tersebut!

Pertanyaan

Suatu basa lemah BOH 0,01 M mempunyai harga pH = 3 - log 2; hitunglah harga Kb basa tersebut!

Pembahasan Soal:

Harga $begin mathsize 14px style K subscript b end style$ larutan basa tersebut dapat ditentukan dari nilai pH sebagai berikut:

$begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row pH equals cell 14 minus sign pOH end cell row pOH equals cell 14 minus sign pH end cell row blank equals cell 14 minus sign left parenthesis 3 minus sign log space 2 right parenthesis end cell row blank equals cell 11 plus log space 2 end cell row cell open square brackets O H to the power of minus sign close square brackets end cell equals cell 10 to the power of negative sign left parenthesis 11 plus log space 2 right parenthesis end exponent end cell row blank equals cell 2 to the power of negative sign 1 end exponent cross times 10 to the power of negative sign 11 end exponent end cell row blank equals cell begin inline style 1 half end style cross times 10 to the power of negative sign 11 end exponent end cell row blank equals cell 0 comma 5 cross times 10 to the power of negative sign 11 end exponent end cell row blank equals cell 5 cross times 10 to the power of negative sign 12 end exponent end cell end table end style$

$begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell open square brackets O H to the power of minus sign close square brackets end cell equals cell square root of K subscript b middle dot M end root end cell row cell 5 middle dot 10 to the power of negative sign 12 end exponent end cell equals cell square root of K subscript b middle dot 0 comma 01 end root end cell row cell left parenthesis 5 middle dot 10 to the power of negative sign 12 end exponent right parenthesis squared end cell equals cell left parenthesis square root of K subscript b middle dot 10 to the power of negative sign 2 end exponent end root right parenthesis squared end cell row cell 25 middle dot 10 to the power of negative sign 24 end exponent end cell equals cell K subscript b middle dot 10 to the power of negative sign 2 end exponent end cell row cell K subscript b end cell equals cell fraction numerator 25 middle dot 10 to the power of negative sign 24 end exponent over denominator 10 to the power of negative sign 2 end exponent end fraction end cell row blank equals cell 2 comma 5 middle dot 10 to the power of negative sign 21 end exponent end cell end table end style$

Jadi, harga $begin mathsize 14px style K subscript italic b end style$ larutan basa tersebut adalah $begin mathsize 14px style bold 2 bold comma bold 5 bold middle dot bold 10 to the power of bold minus sign bold 21 end exponent end style$ .

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 20 Mei 2021

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