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In an experiment, 1 mol kcl is dissolved in a 1.4-kg sample of water, then 1 mol glucose is dissolved in another 1.4-kg sample of water. why does the kcl solution have the higher boiling point?

Respuesta :

Dejanras
Because presence of non-volatile substances (salt-KCl) decreases its mole fraction and the solution's volatility (tendency of a substance to vaporize) and in that way raises the normal boiling point in proportion to the concentration of the solutes (KCl). This is called boiling point elevation (solution has a higher boiling point than a pure solvent). Example is salt water (boils at a higher temperature than pure water).

Answer:This is because the KCl van'T Hoff factor is greater than the van'T Hoff factor of glucose in water.

Explanation:

van't Hoff factor of  KCl =[tex]i_k[/tex] =2

van't Hoff factor of  glucose= [tex]i_g[/tex] =1

Elevation in boiling point is given by:

[tex]\Delta T_b=i\times K_b\times \frac{\text{Number of moles of compound}}{\text{Mass of solvent in kg}}[/tex]

[tex]\Delta T_b\propto i[/tex]

Mass of the water and [tex]K_b[/tex] are same in both solution , [tex]\Delta T_b[/tex] will depend upon van't Hoff factor of the compound.

  • Higher the Van't Hoff number more will be the elevation in boiling point of the solution.
  • Lower the Van'T Hoff number lessor will be elevation is boiling point of the solution.

Since,[tex]i_k>i_g[/tex] which means solution with KCl has more elevation is boiling point than the solution glucose.

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