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Sebanyak sepuluh mililiter larutan kalium asetat  (Mr​ = 98) mempunyai pH = 9. Jika Ka​ CH3​COOH=2,0×10−5 , CH3​COOK yang terlarut dalam 500 ml larutan ialah .... gram. (Ar​ K = 39; C = 12; H = 1; O = 16)

Pertanyaan

Sebanyak sepuluh mililiter larutan kalium asetat  (italic M subscript r = 98) mempunyai pH = 9. Jika K subscript a space C H subscript 3 C O O H equals 2 comma 0 cross times 10 to the power of negative sign 5 end exponent , C H subscript 3 C O O K yang terlarut dalam 500 ml larutan ialah .... gram.

(italic A subscript r K = 39; C = 12; H = 1; O = 16)

  1. 98

  2. 78,4

  3. 39,2

  4. 9,8

  5. 7,8

Q. 'Ainillana

Master Teacher

Mahasiswa/Alumni Universitas Negeri Yogyakarta

Jawaban terverifikasi

Jawaban

jawaban yang benar adalah D. 

Pembahasan

Larutan kalium asetat (C H subscript 3 C O O K) merupakan garam basa. Maka:

pH space C H subscript 3 C O O K space equals space 9 pOH space equals space 14 minus sign 9 pOH space equals space 5 open square brackets O H to the power of minus sign close square brackets space equals space 10 to the power of negative sign 5 end exponent space space space space space space space space space open square brackets O H to the power of minus sign close square brackets space equals space square root of K subscript w over K subscript a space x space open square brackets Garam close square brackets end root space space space space space space space space space space 10 to the power of negative sign 5 end exponent space equals space square root of fraction numerator 1 space x 10 to the power of negative sign 14 end exponent over denominator 1 space x space 10 to the power of negative sign 5 end exponent end fraction space x space open square brackets C H subscript 3 C O O K close square brackets end root space space space space space space space left parenthesis 10 to the power of negative sign 5 end exponent right parenthesis squared space equals space fraction numerator 1 space x 10 to the power of negative sign 14 end exponent over denominator 2 space x space 10 to the power of negative sign 5 end exponent end fraction space x space open square brackets C H subscript 3 C O O K close square brackets open square brackets C H subscript 3 C O O K close square brackets space equals space 10 to the power of negative sign 10 end exponent over 10 to the power of negative sign 9 end exponent open square brackets C H subscript 3 C O O K close square brackets space equals space 0 comma 2 space M  

Setelah konsentrasi kalium asetat diketahui, maka dapat menentukan massanya sebagai berikut:

open square brackets C H subscript 3 C O O K close square brackets space equals space n over V open square brackets C H subscript 3 C O O K close square brackets space equals space fraction numerator begin display style massa over M subscript r end style over denominator V end fraction space space space space space space space space Massa space equals open square brackets C H subscript 3 C O O K close square brackets space space x space V space x space M subscript r space space space space space space space space Massa space equals 0 comma 2 space x space 0 comma 5 space x space 98 space space space space space space space space Massa space equals 9 comma 8 space gram   

 Jadi, jawaban yang benar adalah D. 

818

5.0 (2 rating)

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Arman mencampurkan 50 mL CH3​COOH 0,1 M dengan 50 mL NaOH 0,1 M, setelah diaduk dicelupkan indikator universal menunjukkan xx pada angka .... (Ka​ CH3​COOH=2×10−5, log 5 = 0,7)

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Jawaban terverifikasi

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