Roboguru

Suatu basa lemah LOH mempunyai pH = 10 + log 5 dan Kb LOH = . maka konsentrasi basa tersebut adalah....

Pertanyaan

Suatu basa lemah LOH mempunyai pH = 10 + log 5 dan Kb LOH = 2 comma 5 cross times 10 to the power of negative sign 5 end exponent. maka konsentrasi basa tersebut adalah....space 

Pembahasan Soal:

Langkah pertama adalah menentukan berapkah konsentrasi dari O H to the power of minus sign berdasarkan nilai pH nya


table attributes columnalign right center left columnspacing 0px end attributes row pH equals cell 10 plus log space 5 end cell row pOH equals cell 4 minus sign log space 5 end cell row cell open square brackets O H to the power of minus sign close square brackets end cell equals cell 5 cross times 10 to the power of negative sign 4 end exponent end cell end table


Untuk menentukan konsentrasi basa lemah tersebut dapat menggunakan rumus penentuan pH basa lemah yaitu


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 left square bracket Basa space lemah right square bracket end root end cell row cell 5 cross times 10 to the power of negative sign 4 end exponent end cell equals cell square root of 2 comma 5 cross times 10 to the power of negative sign 5 end exponent cross times left square bracket Basa space lemah right square bracket end root end cell row cell left square bracket basa space lemah right square bracket end cell equals cell fraction numerator 2 comma 5 cross times 10 to the power of negative sign 7 end exponent over denominator 2 comma 5 cross times 10 to the power of negative sign 5 end exponent end fraction end cell row blank equals cell 0 comma 01 space M end cell end table 


Oleh karena itu, konsentrasi basa lemah tersebut adalah 0,01M.space 

Pembahasan terverifikasi oleh Roboguru

Dijawab oleh:

A. Muhammad

Mahasiswa/Alumni Universitas Pendidikan Indonesia

Terakhir diupdate 06 Juni 2021

Roboguru sudah bisa jawab 91.4% pertanyaan dengan benar

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Pertanyaan yang serupa

Lengkapilah tabel berikut

Pembahasan Soal:

Senyawa begin mathsize 14px style N H subscript 3 end style merupakan senyawa basa lemah yang akan terioniasi sebagian sehingga untuk menentukan konsentrasi ion undefined yang terbentuk menjadi


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 alpha cross times open square brackets Basa close square brackets end cell row blank equals cell 0 comma 01 cross times 0 comma 1 M end cell row blank equals cell 0 comma 001 M end cell row pOH equals cell negative sign log space 1 cross times 10 to the power of negative sign 3 end exponent end cell row blank equals cell 3 minus sign log space 1 end cell row pH equals cell 14 minus sign 3 end cell row blank equals 11 end table end style


Jadi, pH larutan undefined 0,1 M adalah 11.undefined 

0

Roboguru

Suatu obat baru yang diperoleh dari ekstrak bijih tanaman ternyata berupa basa organik yang lemah. Apabila 0,1 M larutan obat tersebut dalam air mempunyai , tentukan harga  obat tersebut!

Pembahasan Soal:

Pertama kita tentukan dulu pOH basa lemah tersebut, kemudian kita hitung nilai begin mathsize 14px style K subscript b end style melaui persamaan begin mathsize 14px style open square brackets O H to the power of minus sign close square brackets end style untuk basa lemah:


begin mathsize 14px style pOH equals 14 minus sign pH pOH equals 14 minus sign 11 pOH equals 3   open square brackets O H to the power of minus sign close square brackets equals 10 to the power of negative sign 3 end exponent open square brackets O H to the power of minus sign close square brackets double bond K subscript b cross times M subscript b 10 to the power of negative sign 3 end exponent equals K subscript b cross times 0 comma 1 space M K subscript b equals 10 to the power of negative sign 3 end exponent over 10 to the power of negative sign 1 end exponent K subscript b equals 10 to the power of negative sign 2 end exponent end style  


Jadi, nilai undefined basa lemah tersebut adalah begin mathsize 14px style 10 to the power of negative sign 2 end exponent end style.undefined

0

Roboguru

Suatu basa lemah BOH 0,01 M mempunyai nilai pH = 9 - log 2. Hitunglah nilai  basa tersebut

Pembahasan Soal:

Tetapan ionisasi basa begin mathsize 14px style open parentheses K subscript b close parentheses end style dapat dicari dengan beberapa langkah  berikut:

  • Menghitung open square brackets H to the power of plus sign close square brackets

table attributes columnalign right center left columnspacing 0px end attributes row pH equals cell negative sign log space open square brackets H to the power of plus sign close square brackets end cell row cell 9 minus sign log space 2 space end cell equals cell negative sign log space open square brackets H to the power of plus sign close square brackets end cell row cell 2 cross times 10 to the power of negative sign 9 end exponent end cell equals cell open square brackets H to the power of plus sign close square brackets end cell end table

  • Menghitung open square brackets O H to the power of minus sign close square brackets

table attributes columnalign right center left columnspacing 0px end attributes row cell K subscript w end cell equals cell open square brackets H to the power of plus sign close square brackets cross times open square brackets O H to the power of minus sign close square brackets end cell row cell 1 cross times 10 to the power of negative sign 14 end exponent end cell equals cell 2 cross times 10 to the power of negative sign 9 end exponent cross times open square brackets O H to the power of minus sign close square brackets end cell row cell fraction numerator 1 cross times 10 to the power of negative sign 14 end exponent over denominator 2 cross times 10 to the power of negative sign 9 end exponent end fraction end cell equals cell open square brackets O H to the power of minus sign close square brackets end cell row cell 5 cross times 10 to the power of negative sign 6 end exponent end cell equals cell open square brackets O H to the power of minus sign close square brackets end cell row blank blank blank end table

  • Menghitung K subscript b


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 cell 5 cross times 10 to the power of negative sign 6 end exponent end cell equals cell square root of K subscript b cross times 0 comma 01 space M end root end cell row cell left parenthesis 5 cross times 10 to the power of negative sign 6 end exponent right parenthesis squared end cell equals cell left parenthesis space square root of K subscript b cross times 0 comma 01 space M end root space right parenthesis squared space end cell row cell 25 cross times 10 to the power of negative sign 12 end exponent end cell equals cell K subscript b cross times 10 to the power of negative sign 2 end exponent end cell row cell K subscript b end cell equals cell fraction numerator 25 cross times 10 to the power of negative sign 12 end exponent over denominator 10 to the power of negative sign 2 end exponent end fraction end cell row cell K subscript b end cell equals cell 2 comma 5 cross times 10 to the power of negative sign 9 end exponent end cell row blank blank blank end table 


Jadi, undefined senyawa basa tersebut adalah begin mathsize 14px style 2 comma 5 cross times 10 to the power of negative sign 9 end exponent end style.

0

Roboguru

Lengkapilah tabel berikut

Pembahasan Soal:

Untuk menentukan pH larutan basa maka perlu ditentukan konsentrasi dari ion undefined. Larutan begin mathsize 14px style Fe open parentheses O H close parentheses subscript 3 end style maka menentukan konsentrasi dari ion undefined.
 

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 open square brackets Basa close square brackets end root end cell row blank equals cell square root of 3 cross times 10 to the power of negative sign 5 end exponent cross times 0 comma 2 end root end cell row blank equals cell square root of 6 cross times 10 to the power of negative sign 6 end exponent end root end cell row blank equals cell square root of 6 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 square root of 6 cross times 10 to the power of negative sign 3 end exponent end cell row blank equals cell 3 minus sign log space square root of 6 end cell row pH equals cell 14 minus sign left parenthesis 3 minus sign log square root of 6 right parenthesis end cell row blank equals cell 11 plus log space square root of 6 end cell row blank blank blank end table end style 


Jadi, pH dari larutan undefined 0,2 M adalah begin mathsize 14px style 11 plus log space square root of 6 end style.undefined  

0

Roboguru

Hitunglah pH larutan  0,1 M!

Pembahasan Soal:

Asam N H subscript 3 merupakan basa lemah karena mengalami reaksi ionisasi tidak sempurna di dalam air. Reaksinya adalah sebagai berikut:

N H subscript 3 left parenthesis italic a italic q right parenthesis plus H subscript 2 O open parentheses italic l close parentheses equilibrium N H subscript 4 to the power of plus left parenthesis italic a italic q right parenthesis plus O H to the power of minus sign left parenthesis italic a italic q right parenthesis  

Reaksi tersebut merupakan reaksi kesetimbangan yang memiliki tetapan kesetimbahangan ionisasi basa lemah K subscript italic b. Kosentrasi ion O H to the power of minus sign dengan K subscript italic b memiliki hubungan sesuai persamaan berikut :

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 italic b cross times M subscript italic b end root 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 10 to the power of negative sign 5 end exponent cross times 10 to the power of negative sign 1 end exponent end root 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 10 to the power of negative sign 6 end exponent end root 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 space M end cell row blank blank blank 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 pOH equals cell negative sign log space open square brackets 10 to the power of negative sign 3 end exponent space M close square brackets end cell row pOH equals 3 row blank blank blank row pH equals cell 14 minus sign pOH end cell row pH equals cell 14 minus sign 3 end cell row pH equals 11 end table  

Jadi pH N H subscript bold 3 adalah 11.space 

0

Roboguru

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