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Penambahan 5 ml larutan amonium klorida 0,5 M ke dalam 100 mL  0,5 M (), mengakibatkan .... (log 3,6 = 0,55 dan log 3 = 0,48)

Pertanyaan

Penambahan 5 ml larutan amonium klorida 0,5 M ke dalam 100 mL begin mathsize 14px style N H subscript 4 O H end style 0,5 M (begin mathsize 14px style K subscript b equals 1 comma 8 cross times 10 to the power of negative sign 5 end exponent end style), mengakibatkan ....
(log 3,6 = 0,55 dan log 3 = 0,48)

  1. kenaikan pH sebesar 0,90 space

  2. kenaikan pH sebesar 1,99 space

  3. penurunan pH sebesar 0,92 space

  4. penurunan pH sebesar 1,99 space

  5. penurunan pH sebesar 2,09space 

Pembahasan Soal:

Penambahan 5 ml larutan amonium klorida 0,5 M ke dalam 100 mL begin mathsize 14px style N H subscript 4 O H end style 0,5 M (begin mathsize 14px style K subscript b equals 1 comma 8 cross times 10 to the power of negative sign 5 end exponent end style), mengakibatkan ....
(log 3,6 = 0,55 dan log 3 = 0,48)

pH awal ditentukan oleh larutan basa lemah begin mathsize 14px style N H subscript 4 O H 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 cross times M subscript b end root end cell row blank equals cell square root of 1 comma 8 cross times 10 to the power of negative sign 5 end exponent cross times 0 comma 5 end root end cell row blank equals cell square root of 0 comma 9 cross times 10 to the power of negative sign 5 end exponent end root end cell row blank equals cell square root of 9 cross times 10 to the power of negative sign 6 end exponent end root end cell row blank equals cell 3 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 close square brackets end cell row blank equals cell negative sign log space 3 cross times 10 to the power of negative sign 3 end exponent end cell row blank equals cell 3 minus sign log space 3 end cell row blank equals cell 3 minus sign 0 comma 48 end cell row blank equals cell 2 comma 52 end cell row cell pH and pOH end cell equals 14 row pH equals cell 14 minus sign 2 comma 52 end cell row blank equals cell 11 comma 48 end cell end table end style 

Setelah ditambahkan garam begin mathsize 14px style N H subscript 4 Cl end style akan membentuk larutan penyangga, maka pH ditentukan dengan:

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 K subscript b cross times fraction numerator open square brackets N H subscript 4 O H close square brackets over denominator open square brackets N H subscript 4 Cl close square brackets end fraction end cell row blank equals cell 1 comma 8 cross times 10 to the power of negative sign 5 end exponent cross times fraction numerator fraction numerator 100 space mL cross times 0 comma 5 space M over denominator 105 space mL end fraction over denominator fraction numerator 5 space mL cross times 0 comma 5 space M over denominator 105 space mL end fraction end fraction end cell row blank equals cell 36 cross times 10 to the power of negative sign 5 end exponent end cell row blank equals cell 3 comma 6 cross times 10 to the power of negative sign 4 end exponent end cell row pOH equals cell negative sign log space open square brackets O H to the power of minus sign close square brackets end cell row blank equals cell negative sign log space 3 comma 6 cross times 10 to the power of negative sign 4 end exponent end cell row blank equals cell 4 minus sign log space 3 comma 6 end cell row blank equals cell 4 minus sign 0 comma 55 end cell row blank equals cell 3 comma 45 end cell row cell pH and pOH end cell equals 14 row pH equals cell 14 minus sign 3 comma 45 end cell row blank equals cell 10 comma 55 end cell end table end style 

pH menjadi turun, dari 11,48 menjadi 10,55 yaitu sebesar 0,93.

Jadi, jawaban yang benar adalah C.

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 11 April 2021

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