Question

Some ethylene glycol(hoch2ch2oh)is added your cars cooling system along with 5 kg of water. if the freezing point of water glycolsolution is -150c, what is the boiling point of the the solution?

Answer 1

Answer: $377.12K$

Explanation:

Depression in freezing point :

$\Delta T_f=k_f\times m$

or,

$\Delta T_f=k_f\times \frac{\text{ Moles of solute}}{\text{ Mass of solvent in kg}}$

where,

$T_f$ = change in freezing point

$k_f$ = freezing point constant= 1.86 K kg/mol

m = molality

$\Delta T_f=T^{o}_f-T_f=0^0C-(-15^0C)$=15^0C[/tex]

$15=1.86 K kg/mol\times \frac{\text{ Moles of solute}}{5kg }}$

${\text{ Moles of solute}}=40.32 moles$

Elevation in boiling point:

$\Delta T_b=K_b\times \frac{\text {Moles of solute}}{\text{weight of solvent in kg}}$

$T_b-T_b^0=0.512\times \frac{40.32}{5kg}$

$T_b-373K=0.512\times \frac{40.32}{5kg}$

$T_b=377.12K$

Answer 2

Explanation:

Boiling point will be = 377 . 12 k