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Berapakah pH larutan yang terbentuk dari campuran 200 mL larutan  dengan 800 mL larutan KOH (pH = 12)?

Pertanyaan

Berapakah pH larutan yang terbentuk dari campuran 200 mL larutan begin mathsize 14px style H subscript 2 S O subscript 4 space left parenthesis pH space equals 3 right parenthesis end style dengan 800 mL larutan KOH (pH = 12)?space 

Pembahasan Video:

Pembahasan Soal:

Sebanyak 200 mL larutan asam kuat begin mathsize 14px style H subscript 2 S O subscript 4 end style dengan pH 3 direaksikan dengan 800 mL larutan basa kuat begin mathsize 14px style K O H end style yang memiliki pH 12. Adapun tahapan untuk menentukan pH larutan campuran sebagai berikut.

Menentukan mol masing-masing larutan
    Menentukan mol begin mathsize 14px style H subscript 2 S O subscript 4 space end style 

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row pH equals 3 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 3 end exponent end cell row cell H subscript 2 S O subscript 4 end cell rightwards arrow cell 2 H to the power of plus sign plus S O subscript 3 to the power of 2 minus sign end exponent end cell row cell open square brackets H to the power of plus sign close square brackets end cell equals cell valensi cross times Ma end cell row cell 10 to the power of negative sign 3 end exponent end cell equals cell 2 cross times Ma end cell row Ma equals cell 5 cross times 10 to the power of negative sign 4 end exponent space M end cell row blank blank blank row cell mol space H subscript 2 S O subscript 4 end cell equals cell M cross times V end cell row blank equals cell 5 cross times 10 to the power of negative sign 4 end exponent space M cross times 200 space mL end cell row blank equals cell 0 comma 1 space mmol space space end cell end table end style 

Perhitungan yang sama juga dilakukan untuk larutan undefined.

begin mathsize 14px style table attributes columnalign right center left columnspacing 0px end attributes row pH equals 12 row pOH equals 2 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 2 end exponent end cell row cell K O H end cell rightwards arrow cell K to the power of plus sign and O H to the power of minus sign end cell row cell open square brackets O H to the power of minus sign close square brackets end cell equals cell valensi cross times Mb end cell row cell 10 to the power of negative sign 2 end exponent end cell equals cell 1 cross times Mb end cell row Mb equals cell 10 to the power of negative sign 2 end exponent space M end cell row blank blank blank row cell mol space K O H end cell equals cell M cross times V end cell row blank equals cell 10 to the power of negative sign 2 end exponent M cross times 800 space mL end cell row blank equals cell 8 space mmol space end cell end table end style 


Setelah mol masing-masing larutan diketahui, persamaan reaksi dapat dihitung.

 

pada reaksi asam kuat dan basa kuat terdapat sisa mol dari asam kuat, sehingga pH konsentrasi campuran dapat dihitung sebagai berikut:


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 campuran close square brackets space end cell equals cell space fraction numerator sisa space mol space basa over denominator V space total end fraction end cell row blank equals cell space fraction numerator 7 comma 8 space mmol over denominator 1000 space mL end fraction end cell row blank equals cell space 7 comma 8 cross times 10 to the power of negative sign 3 end exponent end cell row pOH equals cell negative sign log space open square brackets O H to the power of minus sign campuran close square brackets end cell row cell pOH space end cell equals cell space 3 minus sign log 7 comma 8 end cell row pH equals cell 14 minus sign pOH end cell row blank equals cell 14 minus sign left parenthesis 3 minus sign log space 7 comma 8 right parenthesis end cell row blank equals cell 11 plus log space 7 comma 8 space space end cell end table end style 


Jadi, pH capuran larutan adalah begin mathsize 14px style bold 11 bold plus bold log bold 7 bold comma bold 8 end style.undefined 

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 20 Juli 2021

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