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Asam lemah HA memiliki nilai tetapan disosiasi begin mathsize 14px style K subscript a equals 10 to the power of negative sign 7 end exponent end style . Diantara pernyataan berikut ini:

i. begin mathsize 14px style open square brackets A to the power of minus sign close square brackets less than less than open square brackets HA close square brackets end style  

ii. begin mathsize 14px style H to the power of plus sign equals open parentheses K subscript a open square brackets HA close square brackets close parentheses to the power of 1 forward slash 2 end exponent end style 

iii. begin mathsize 14px style open square brackets O H to the power of minus sign close square brackets greater than greater than open square brackets A to the power of minus sign close square brackets end style 

yang benar untuk asam lemah 0,3 M HA dalam air adalah ....

N. Puspita

Master Teacher

Jawaban terverifikasi

Jawaban

pernyataan yang benar ditunjukkan oleh pernyataan i dan ii.

Pembahasan

Analisis pilihan jawaban:

Pilihan jawaban i. begin mathsize 14px style open square brackets A to the power of minus sign close square brackets less than less than open square brackets HA close square brackets end style dan Pilihan jawaban ii. begin mathsize 14px style H to the power of plus sign equals open parentheses K subscript a open square brackets HA close square brackets close parentheses to the power of 1 forward slash 2 end exponent end style 

Reaksi ionisasi asam lemah:

begin mathsize 14px style HA left parenthesis italic a italic q right parenthesis equilibrium H to the power of plus sign left parenthesis italic a italic q right parenthesis plus A to the power of minus sign left parenthesis italic a italic q right parenthesis end style 

setiap satu mol senyawa HA yang terionisasi akan menghasilkan satu mol ion begin mathsize 14px style H to the power of plus sign end style dan satu mol ion begin mathsize 14px style A to the power of minus sign end style . Oleh karena itu, konsentrasi ion begin mathsize 14px style H to the power of plus sign end style dan begin mathsize 14px style A to the power of minus sign end style yang berasal dari HA adalah sama, undefined 

Karena begin mathsize 14px style open square brackets H to the power of plus sign close square brackets double bond open square brackets A to the power of minus sign close square brackets end style, maka begin mathsize 14px style open square brackets A to the power of minus sign close square brackets end style dapat disubstitusi dengan begin mathsize 14px style open square brackets H to the power of plus sign close square brackets end style, oleh karena itu:

begin mathsize 14px style K subscript a equals fraction numerator open square brackets H to the power of plus sign close square brackets cross times open square brackets A to the power of minus sign close square brackets over denominator open square brackets HA close square brackets end fraction end style   

menjadi:

 begin mathsize 14px style K subscript a equals fraction numerator open square brackets H to the power of plus sign close square brackets cross times open square brackets H to the power of plus sign close square brackets over denominator open square brackets HA close square brackets end fraction end style  

Mencari rumus begin mathsize 14px style open square brackets H to the power of plus sign close square brackets end style

begin mathsize 14px style K subscript a equals fraction numerator open square brackets H to the power of plus sign close square brackets squared over denominator open square brackets HA close square brackets end fraction end style 

 begin mathsize 14px style open square brackets H to the power of plus sign close square brackets squared equals Ka cross times open square brackets HA close square brackets end style  

 begin mathsize 14px style open square brackets H to the power of plus sign close square brackets equals left parenthesis K subscript a cross times open square brackets HA close square brackets right parenthesis to the power of 1 forward slash 2 end exponent end style 

Jadi, pilihan jawaban ii adalah benar

Menghitung nilai undefined yaitu:

begin mathsize 14px style open square brackets H to the power of plus sign close square brackets equals left parenthesis K subscript a cross times open square brackets HA close square brackets right parenthesis to the power of 1 forward slash 2 end exponent space open square brackets H to the power of plus sign close square brackets equals left parenthesis 1 middle dot 10 to the power of negative sign 7 end exponent cross times 3 middle dot 10 to the power of negative sign 1 end exponent right parenthesis to the power of 1 forward slash 2 end exponent open square brackets H to the power of plus sign close square brackets equals left parenthesis 3 middle dot 10 to the power of negative sign 8 end exponent right parenthesis to the power of 1 forward slash 2 end exponent open square brackets H to the power of plus sign close square brackets equals square root of left parenthesis 3 middle dot 10 to the power of negative sign 8 end exponent right parenthesis end root open square brackets H to the power of plus sign close square brackets equals 1 comma 73 middle dot 10 to the power of negative sign 4 end exponent space M end style 

Oleh karena itu

 begin mathsize 14px style open square brackets A to the power of minus sign close square brackets double bond open square brackets H to the power of plus sign close square brackets equals 1 comma 73 middle dot 10 to the power of negative sign 4 end exponent space M dan open square brackets HA close square brackets equals 3 middle dot 10 to the power of negative sign 1 space end exponent M maka colon open square brackets A to the power of minus sign close square brackets less than less than open square brackets HA close square brackets end style 

Jadi, pilihan jawaban i adalah benar

 

Pilihan jawaban iii. begin mathsize 14px style open square brackets O H to the power of minus sign close square brackets greater than greater than open square brackets A to the power of minus sign close square brackets end style

Karena senyawa HA merupakan senyawa asam 

begin mathsize 14px style open square brackets H to the power of plus sign close square brackets double bond open square brackets A to the power of minus sign close square brackets dan open square brackets H to the power of plus sign close square brackets greater than greater than open square brackets O H to the power of minus sign close square brackets maka open square brackets A to the power of minus sign close square brackets greater than greater than open square brackets O H to the power of minus sign close square brackets atau open square brackets O H to the power of minus sign close square brackets less than less than open square brackets A to the power of minus sign close square brackets end style  

Jadi, pilihan jawaban iii adalah salah

 

Jadi, pernyataan yang benar ditunjukkan oleh pernyataan i dan ii.

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