Question

Determine the required concentration (in percent by mass) for an aqueous ethylene glycol (C2H6O2) solution to have a boiling point of 106.2 ∘C

Answer 1

$\Delta$T_boil = i⋅K_b⋅C_m

C_m = ΔT_boil / K_b = 6.2 / 0.512 = 12.11 (mol/kg_H2O)

m_C2H6O2 = n_C2H6O2⋅M_C2H6O2 = 12.11⋅62 = 750.82 (g)

m_solution = 1000 + 750.82 = 1750.82 (g)

$\omega$_C2H6O2 = 100⋅m_C2H6O2 / m_solution = 100⋅750.82 / 1750.82 = 42.88 %

Answer: 42.88 %.