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Campuran yang terdiri dari 100 mL  0,1 M  dan 100 mL  0,2 M akan memiliki pH sebesar...

Pertanyaan

Campuran yang terdiri dari 100 mL begin mathsize 14px style H F end style 0,1 M begin mathsize 14px style left parenthesis K subscript a equals 2 cross times 10 to the power of negative sign 5 end exponent right parenthesis end style dan 100 mL begin mathsize 14px style Na F end style 0,2 M akan memiliki pH sebesar...undefined 

  1. undefined undefined 

  2. begin mathsize 14px style 5 plus log space 9 end style undefined 

  3. begin mathsize 14px style 9 minus sign log space 5 end style undefined 

  4. begin mathsize 14px style 9 end style undefined 

  5. begin mathsize 14px style 9 plus log space 5 end style undefined 

Pembahasan Soal:

Campuran di atas merupakan larutan penyangga bersifat asam karena terdiri dari asam lemah dan garamnya. Reaksinya sebagai berikut.

begin mathsize 14px style H F left parenthesis italic a italic q right parenthesis equilibrium H to the power of plus sign left parenthesis italic a italic q right parenthesis plus F to the power of minus sign left parenthesis italic a italic q right parenthesis Na F left parenthesis italic a italic q right parenthesis yields Na to the power of plus sign left parenthesis italic a italic q right parenthesis plus F to the power of minus sign left parenthesis italic a italic q right parenthesis end style  

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row cell open square brackets H to the power of plus sign close square brackets end cell equals cell K subscript italic a cross times fraction numerator mol space asam space lemah over denominator mol space garam end fraction end cell row cell open square brackets H to the power of plus sign close square brackets end cell equals cell K subscript italic a cross times fraction numerator mmol space H F over denominator mmol space Na F end fraction end cell row cell open square brackets H to the power of plus sign close square brackets end cell equals cell K subscript italic a cross times fraction numerator V space H F cross times M space H F over denominator V space Na F cross times M space Na F end fraction end cell row cell open square brackets H to the power of plus sign close square brackets end cell equals cell 2 cross times 10 to the power of negative sign 5 end exponent cross times fraction numerator 100 space mL cross times 0 comma 1 space mmol space mL to the power of negative sign 1 space end exponent over denominator 100 space mL cross times 0 comma 2 space mmol space m L space to the power of negative sign 1 end exponent end fraction end cell row cell open square brackets H to the power of plus sign close square brackets end cell equals cell 2 cross times 10 to the power of negative sign 5 end exponent cross times fraction numerator 10 space mmol over denominator 20 space mmol end fraction end cell row cell open square brackets H to the power of plus sign close square brackets end cell equals cell 10 to the power of negative sign 5 end exponent space M end cell row blank blank blank row pH equals cell negative sign log open square brackets H to the power of plus sign close square brackets end cell row pH equals cell negative sign log left square bracket 10 to the power of negative sign 5 end exponent M right square bracket end cell row pH equals 5 row blank blank blank row blank blank blank end table end style 

Jadi pH campurannya adalah 5.

Oleh karena itu, jawaban yang benar adalah A.undefined 

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 02 April 2021

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