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Jika pH larutan 0,01 M suatu asam lemah HA adalah 3,5. maka tetapan asam () adalah...

Pertanyaan

Jika pH larutan 0,01 M suatu asam lemah HA adalah 3,5. maka tetapan asam (begin mathsize 14px style K subscript italic a end style) adalah...

  1. begin mathsize 14px style 1 cross times 10 to the power of negative sign 3 end exponent end style 

  2. begin mathsize 14px style 2 cross times 10 to the power of negative sign 3 end exponent end style 

  3. begin mathsize 14px style 1 cross times 10 to the power of negative sign 5 end exponent end style 

  4. begin mathsize 14px style 1 cross times 10 to the power of negative sign 7 end exponent end style 

  5. begin mathsize 14px style 1 cross times 10 to the power of negative sign 8 end exponent end style 

Pembahasan Soal:

Salah satu ciri-ciri asam lemah yaitu memiliki tetapan ionisasi asam begin mathsize 14px style open parentheses K subscript a close parentheses end style. Untuk mengetahui pH senyawa asam digunakan rumus:

table attributes columnalign right center left columnspacing 0px end attributes row blank blank cell open square brackets H to the power of plus sign close square brackets end cell end table table attributes columnalign right center left columnspacing 0px end attributes row blank equals blank end table table attributes columnalign right center left columnspacing 0px end attributes row blank blank cell square root of K subscript a cross times M subscript a end root end cell end table 

1. Menghitung nilai [H+]

pH equals minus sign log space open square brackets H to the power of plus sign close square brackets 3 comma 5 equals minus sign log space open square brackets H to the power of plus sign close square brackets space open square brackets H to the power of plus sign close square brackets equals 1 cross times 10 to the power of negative sign 3 comma 5 space end exponent M 

2. Menghitung nilai Ka

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 a cross times M subscript a end root end cell row cell 1 cross times 10 to the power of negative sign 3 comma 5 end exponent end cell equals cell square root of K subscript a cross times 0 comma 01 space end root end cell row cell left parenthesis 1 cross times 10 to the power of negative sign 3 comma 5 end exponent right parenthesis squared end cell equals cell left parenthesis square root of K subscript a cross times left parenthesis 1 cross times 10 to the power of negative sign 2 end exponent right parenthesis space end root right parenthesis squared end cell row cell 1 cross times 10 to the power of negative sign 7 end exponent end cell equals cell K subscript a cross times left parenthesis 1 cross times 10 to the power of negative sign 2 end exponent space right parenthesis end cell row cell K subscript a end cell equals cell fraction numerator 1 cross times 10 to the power of negative sign 7 end exponent over denominator 1 cross times 10 to the power of negative sign 2 end exponent end fraction space end cell row blank equals cell 1 cross times 10 to the power of negative sign 5 end exponent space M end cell end table  

Ka asam lemah HA adalah 1 cross times 10 to the power of negative sign 5 end exponent 

Jadi, jawaban yang benar adalah C.

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 03 Juni 2021

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