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Membuat kurva titrasi 50 mL CH3COOH 0,05 M dengan NaOH 0,1 M. Ka CH3COOH =   Gunakan tabel berikut untuk menentukan titik dalam kurva.

Pertanyaan

Membuat kurva titrasi 50 mL CH3COOH 0,05 M dengan NaOH 0,1 M.

Ka CH3COOH = 1 comma 8 cross times 10 to the power of negative sign 5 end exponent 

Gunakan tabel berikut untuk menentukan titik dalam kurva. 

Pembahasan Soal:

Untuk menentukan pH larutan dari titrasi larutan CH3COOH dan NaOH, dengan cara sebagai berikut :

a) pH CH3COOH sebelum ditambah NaOH

open square brackets H to the power of plus sign close square brackets equals square root of K subscript a cross times M end root open square brackets H to the power of plus sign close square brackets equals square root of 1 comma 8 cross times 10 to the power of negative sign 5 end exponent cross times 0 comma 05 end root open square brackets H to the power of plus sign close square brackets equals 3 cross times 10 to the power of negative sign 3 comma 5 end exponent pH equals minus sign log space open square brackets H to the power of plus sign close square brackets pH equals minus sign log space open parentheses 3 cross times 10 to the power of negative sign 3 comma 5 end exponent close parentheses pH equals 3 comma 5 minus sign log space 3 equals 3 comma 02 

b) pH larutan CH3COOH setelah ditambah NaOH sebanyak 10 mL

mol space C H subscript 3 C O O H double bond M cross times V equals 0 comma 05 cross times 50 equals 2 comma 5 space mmol mol space Na O H double bond M cross times V equals 0 comma 1 cross times 10 equals 1 space mmol 

Persamaan reaksi asam - basa :

Pada reaksi asam-basa diatas, mmol CH3COOH bersisa maka larutan yang terbentuk adalah larutan penyangga asam. Rumus untuk menentukan pH larutan penyangga asam :

open square brackets H to the power of plus sign close square brackets equals K subscript a cross times fraction numerator mol space C H subscript 3 C O O H over denominator mol space C H subscript 3 C O O Na end fraction open square brackets H to the power of plus sign close square brackets equals 1 comma 8 cross times 10 to the power of negative sign 5 end exponent cross times fraction numerator 1 comma 5 over denominator 1 end fraction open square brackets H to the power of plus sign close square brackets equals 2 comma 7 cross times 10 to the power of negative sign 5 end exponent space M pH equals minus sign log space open square brackets H to the power of plus sign close square brackets space space space space equals minus sign log space left parenthesis 2 comma 7 cross times 10 to the power of negative sign 5 end exponent right parenthesis pH equals 5 minus sign log space 2 comma 7 equals 4 comma 57  

c) pH larutan CH3COOH setelah ditambah NaOH sebanyak 20 mL.

mol space C H subscript 3 C O O H double bond M cross times V equals 0 comma 05 cross times 50 equals 2 comma 5 space mmol mol space Na O H double bond M cross times V equals 0 comma 1 cross times 20 equals 2 space mmol 

Persamaan reaksi asam - basa :

Pada reaksi asam-basa diatas, mmol CH3COOH bersisa maka larutan yang terbentuk adalah larutan penyangga asam. Rumus untuk menentukan pH larutan penyangga asam :

open square brackets H to the power of plus sign close square brackets equals K subscript a cross times fraction numerator mol space C H subscript 3 C O O H over denominator mol space C H subscript 3 C O O Na end fraction open square brackets H to the power of plus sign close square brackets equals 1 comma 8 cross times 10 to the power of negative sign 5 end exponent cross times fraction numerator 0 comma 5 over denominator 2 end fraction open square brackets H to the power of plus sign close square brackets equals 4 comma 5 cross times 10 to the power of negative sign 6 end exponent space M pH equals minus sign log space open square brackets H to the power of plus sign close square brackets space space space space equals minus sign log space left parenthesis 4 comma 5 cross times 10 to the power of negative sign 6 end exponent right parenthesis pH equals 6 minus sign log space 4 comma 5 equals 5 comma 35 

d) pH larutan CH3COOH setelah ditambah NaOH sebanyak 25 mL

mol space C H subscript 3 C O O H double bond M cross times V equals 0 comma 05 cross times 50 equals 2 comma 5 space mmol mol space Na O H double bond M cross times V equals 0 comma 1 cross times 25 equals 2 comma 5 space mmol 

Persamaan reaksi asam - basa :

 

Pada reaksi asam-basa diatas, mmol CH3COOH = mmol NaOH maka larutan yang terbentuk adalah hidrolisis garam yang bersifat basa. Rumus untuk menentukan pH larutan garamnya:

open square brackets O H to the power of minus sign close square brackets equals square root of K subscript w over K subscript a cross times open square brackets C H subscript 3 C O O Na close square brackets end root open square brackets C H subscript 3 C O O Na close square brackets equals fraction numerator mmol space sisa over denominator Vtotal end fraction equals fraction numerator 2 comma 5 over denominator 75 end fraction equals 1 over 30 M open square brackets O H to the power of minus sign close square brackets equals square root of fraction numerator 10 to the power of negative sign 14 end exponent over denominator 1 comma 8 cross times 10 to the power of negative sign 5 end exponent end fraction cross times 1 over 30 end root open square brackets O H to the power of minus sign close square brackets equals 4 comma 3 cross times 10 to the power of negative sign 6 end exponent space M pOH equals minus sign log space open square brackets O H to the power of minus sign close square brackets space space space space space space space equals minus sign log space open parentheses 4 comma 3 cross times 10 to the power of negative sign 6 end exponent close parentheses pOH equals 6 minus sign log space 4 comma 3 pH and pOH equals 14 pH equals 14 minus sign open parentheses 6 minus sign log space 4 comma 3 close parentheses pH equals 8 plus log space 4 comma 3 equals 8 comma 63  

e) pH larutan CH3COOH setelah ditambah NaOH sebanyak 30 mL

mol space C H subscript 3 C O O H double bond M cross times V equals 0 comma 05 cross times 50 equals 2 comma 5 space mmol mol space Na O H double bond M cross times V equals 0 comma 1 cross times 30 equals 3 space mmol 

Persamaan reaksi asam - basa :

Pada reaksi asam-basa diatas, mmol NaOH bersisa maka larutan yang terbentuk adalah basa kuat. Rumus untuk menentukan pH basa kuat :

open square brackets O H to the power of minus sign close square brackets equals M cross times b space space space space space space space equals fraction numerator 0 comma 5 over denominator 80 end fraction cross times 1 equals 6 comma 25 cross times 10 to the power of negative sign 3 end exponent space M pOH equals minus sign log space open square brackets O H to the power of minus sign close square brackets pOH equals minus sign log space open parentheses 6 comma 25 cross times 10 to the power of negative sign 3 end exponent close parentheses pOH equals 3 minus sign log space 6 comma 25 pH and pOH equals 14 pH equals 14 minus sign open parentheses 3 minus sign log space 6 comma 25 close parentheses pH equals 11 plus log space 6 comma 25 equals 11 comma 80  

Data titrasi 50 mL larutan CH3COOH 0,05 M dengan larutan NaOH 0,1 M

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 18 Mei 2021

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