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11,2 gram dilarutkan dengan air hingga volumenya 5...

11,2 gram begin mathsize 14px style K O H space open parentheses Mr equals 56 close parentheses end style dilarutkan dengan air hingga volumenya 500 ml, tentukan pH larutan tersebut !

  1. 13 - log 4

  2. 13 + log 4

  3. 1 - log 4

  4. 1 + log 4

  5. 13

Jawaban:

Langkah pertama, hitung nilai mol KOH

straight n space equals space straight m over Mr straight n space equals space fraction numerator 11 comma 2 space gram over denominator 56 space begin display style bevelled gram over mol end style end fraction straight n space equals space 0 comma 2 space mol

Langkah kedua, hitung nilai molaritas

straight M space equals space straight n over straight V straight M space equals space fraction numerator 0 comma 2 space mol over denominator 0 comma 5 space straight L end fraction straight M space equals space 0 comma 4 space straight M

Langkah ketiga, hitung nilai left square bracket OH to the power of minus right square bracket

begin mathsize 14px style K O H end style termasuk 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 space space space space equals 4.10 to the power of negative sign 1 end exponent cross times 1 space space space space space space space space space space space equals 4.10 to the power of negative sign 1 end exponent space space space space

Langkah keempat, hitung nilai pOH

pOH equals negative log space open square brackets OH to the power of minus close square brackets space space space space space space space space equals negative log space 4.10 to the power of negative 1 end exponent space space space space space space space space equals 1 minus log space 4

Langkah kelima, hitung nilai pH

pH plus pOH equals 14 space space space space space space space space space space space space pH equals 14 minus left parenthesis 1 minus log space 4 right parenthesis space space space space space space space space space space space space space space space space space equals 13 plus log space 4

Jadi, pH larutan KOH adalah 13 + log 4. Jawaban yang benar adalah B.

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