Question

A 0.5 molal solution of ethylene glycol in water is used as coolant in a car. If the freezing point depression constant of water is 1.86$^\circ$C per mole, the mixture shall freeze at

• A. 0.93$^\circ$C
• B. -0.93$^\circ$C
• C. 1.86$^\circ$C
• D. -1.86$^\circ$C

Answer 1

Answer: (B)

Depression of freezing point
$\Delta T _{ f }= K _{ f } m$
Given that,
$m =0.5$
$K _{ f }=1.86 K - kg / mole$
So,$\Delta T _{ f }=1.86 \times 0.5$
$T _{ f }=0-0.93=-0.93^{0} C$