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Larutan  0,1 M mempunyai pH = 11. pH larutan  0,1 M adalah ....

Pertanyaan

Larutan N H subscript 3 0,1 M mempunyai pH = 11. pH larutan N H subscript 4 Cl 0,1 M adalah ....

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Pembahasan Soal:

Larutan N H subscript 3 merupakan basa lemah, maka: 0,1 M mempunyai pH = 11

table attributes columnalign right center left columnspacing 0px end attributes row pOH equals cell 14 minus sign pH end cell row blank equals cell 14 minus sign 11 end cell row blank equals 3 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 3 equals cell negative sign log space open square brackets O H to the power of minus sign close square brackets 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 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 M subscript b 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 1 end root space kuadratkan space kedua space ruas end cell row cell 10 to the power of negative sign 6 end exponent end cell equals cell K subscript b cross times 10 to the power of negative sign 1 end exponent end cell row cell K subscript b end cell equals cell 10 to the power of negative sign 5 end exponent end cell end table 

Larutan N H subscript 4 Cl merupakan larutan garam yang disusun oleh sisa basa lemah dan sisa asam kuat. Ion sisa basa lemah akan membentuk reaksi kesetimbangan dengan air sehingga melepas ion H to the power of plus sign dengan reaksi berikut:

N H subscript 4 to the power of plus plus H subscript 2 O equilibrium N H subscript 4 O H and H to the power of plus sign 

Sehingga garam ini bersifat asam, persamaan H to the power of plus sign-nya sebagai berikut:

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 square root of K subscript w over K subscript b cross times left square bracket N H subscript 4 to the power of plus right square bracket end root end cell row blank equals cell square root of 10 to the power of negative sign 14 end exponent over 10 to the power of negative sign 5 end exponent cross times 0 comma 1 end root end cell row blank equals cell square root of 10 to the power of negative sign 10 end exponent end root end cell row blank equals cell 10 to the power of negative sign 5 end exponent end cell row pH equals cell negative sign log space open square brackets H to the power of plus sign close square brackets end cell row blank equals cell negative sign log space 10 to the power of negative sign 5 end exponent end cell row blank equals 5 end table 

Jadi, jawbana yang benar adalah B.

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 05 Mei 2021

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