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A student dissolves 0.250 mol NaC1 in 2.05 kg H20. What is the molality of the resulting solution? Show your work.

Respuesta :

Answer:

m = 0.122 m

Explanation:

Molality(m): A measure of the number of moles of solute in a solution corresponding to 1 kg or 1000 g of solvent.

[tex]\mathrm{Molality\:Formula}:\quad \mathrm m = \dfrac{ mole\:of\:solute }{ mass\:of\:solvent\:in\:kg }[/tex]

[tex]\mathrm m = \dfrac{ mole}{ kg }[/tex]

[tex]\mathrm{Substitute\:the\:numbers\:into\:the\:"Molality\:Formula"}[/tex]

[tex]\mathrm m = \dfrac{ 0.250 }{ 2.05 }[/tex]

[tex]\mathrm{Divide\:0.250\:by\:2.05\:and\:get\:0.12195122}[/tex]

[tex]\mathrm m = {0.12195122}[/tex]

[tex]\mathrm{Round\:to\:the\:nearest\:thousandths\:place}[/tex]

[tex]\mathrm m = 0.122[/tex]

  • No of moles of solute(NaCl)=0.250mol
  • Mass of solvent (water) in kg=2.05kg

[tex]\\ \rm\Rrightarrow Molality=\dfrac{Moles\:of\:solute}{Mass\:of\: solvent\:in\:kg}[/tex]

[tex]\\ \rm\Rrightarrow Molality=0.250/2.05[/tex]

[tex]\\ \rm\Rrightarrow Molality=0.1m[/tex]