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Larutan NaOH 2,5 M jika  NaOH = 40 dan massa jenis larutan 1 kg/L, maka fraksi mol NaOH adalah ...

Pertanyaan

Larutan NaOH 2,5 M jika italic M subscript r NaOH = 40 dan massa jenis larutan 1 kg/L, maka fraksi mol NaOH adalah ...

  1. space 

  2. bevelled fraction numerator 2 comma 5 over denominator 52 comma 5 end fraction 

  3. 0,025 space 

  4. 0,125 space 

  5. bevelled fraction numerator 52 comma 5 over denominator 2 comma 5 end fraction 

Pembahasan Soal:

Diketahui: italic M subscript r space H subscript 2 O equals 18 space g space mol to the power of negative sign 1 end exponent (pelarut)

Menentukan massa NaOH dan H subscript 2 O:

table attributes columnalign right center left columnspacing 0px end attributes row cell M subscript NaOH end cell equals cell fraction numerator rho cross times percent sign cross times 10 over denominator italic M subscript r end fraction end cell row cell 2 comma 5 end cell equals cell fraction numerator 1 cross times percent sign cross times 10 over denominator 40 end fraction end cell row percent sign equals cell 100 over 10 end cell row blank equals cell 10 percent sign end cell end table 

table attributes columnalign right center left columnspacing 0px end attributes row cell m subscript NaOH end cell equals cell 10 percent sign cross times 100 end cell row blank equals cell 10 space gram end cell end table 

table attributes columnalign right center left columnspacing 0px end attributes row cell m subscript H subscript 2 O end subscript end cell equals cell 90 percent sign cross times 100 end cell row blank equals cell 90 space gram end cell end table 

Menentukan fraksi mol NaOH:

table attributes columnalign right center left columnspacing 0px end attributes row cell n subscript NaOH end cell equals cell m over italic M subscript r end cell row blank equals cell 10 over 40 end cell row blank equals cell 0 comma 25 space mol end cell end table 

table attributes columnalign right center left columnspacing 0px end attributes row cell n subscript H subscript 2 O end subscript end cell equals cell m over italic M subscript r end cell row blank equals cell 90 over 18 end cell row blank equals cell 5 space mol end cell end table 

table attributes columnalign right center left columnspacing 0px end attributes row cell X subscript NaOH end cell equals cell fraction numerator n subscript NaOH and n subscript H subscript 2 O end subscript over denominator n subscript NaOH end fraction end cell row blank equals cell fraction numerator 0 comma 25 plus 5 over denominator 0 comma 25 end fraction end cell row blank equals cell fraction numerator 5 comma 25 over denominator 0 comma 25 end fraction end cell end table 

Maka fraksi mol NaOH adalah bevelled fraction numerator 52 comma 5 over denominator 2 comma 5 end fraction.

Jadi, jawaban yang benar adalah E.

Pembahasan terverifikasi oleh Roboguru

Terakhir diupdate 10 Juni 2021

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