38. What is the expected boiling point of a solution prepared by dissolving 6.37 g of sodium iodide (Nal) in 48.6 g of water (H 0)? K'b (ater)-0.512"Cm a) 0.90°C d) 103.26"C b) 100.45°C e) None of the above c) 100.90°C

Respuesta :

Answer: c) 100.90°C

Explanation:

Elevation in boiling point is given by:

[tex]\Delta T_b=i\times K_b\times m[/tex]

[tex]\Delta T_b=T_b-T_b^0[/tex] = elevation in boiling point

i= vant hoff factor = 2 (for NaI[/tex]

[tex]NaI\rightarrow Na^++I^-[/tex]

[tex]K_b[/tex] = boiling point constant = [tex]0.512^0C/m[/tex]

m= molality  

[tex]\Delta T_b=i\times K_b\times \frac{\text{mass of solute}}{\text{molar mass of solute}\times \text{weight of solvent in kg}}[/tex]

Weight of solvent i kg =48.6 g= 0.0486kg

[tex]\Delta T_b=2\times 0.512\times \frac{6.37g}{150g/mol\times 0.0486[/tex]

[tex]\Delta T_b=2\times 0.512\times \frac{6.37g}{150g/mol\times 0.0486[/tex]

[tex]\Delta T_b=0.9^0C[/tex]

[tex](T_b-1000)^0C=0.9^0C[/tex]

[tex]T_b=100.9^0C[/tex]

Thus the boiling point of the solution will be [tex]100.90^0C[/tex].