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Pertanyaan

fraksi mol urea dalam larutn yg dibuat dgn melarutkn 30 gr urea (Mr=60) ke dlm 0,09kg air(Mr=18) ?

A ½
B 1/10
C 1/11
D 1/5
E 5

2 Jawaban

  • mol = massa/Mr

    mol urea = 30/60 = 1/2 mol

    mol air = 90/18 = 5

    Xt = nt / nt + np

       = (1/2) / (1/2) + 5 = (1/2) / 11/2 =1/11
  • Mol urea = gr/Mr = 30/60
    = 0.5
    Mol air = gr/Mr = (0.09×1000)/18
    = 5
    Fraksi mol = mol urea/mol campuran
    = 0.5/0.5+5
    = 0.090 = 1/11 ( C )

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