0.5 molal solution of ethylene glycol in water is used as a coolant in car. If the freezing point depression constant of water is 1.86oCkg per mole, the mixture will freeze at

Question

0.5 molal solution of ethylene glycol in water is used as a coolant in car. If the freezing point depression constant of water is 1.86oCkg per mole, the mixture will freeze at (A) 0.93oC (B) - 0.93oC (C) 1.86oC (D) - 1.86oC

Tardigrade Admin · Accepted Answer

Δ Tf=kf× m =1.86× 0.5=0.93oC ∴ Δ Tf= Tfo-Tf ∴ Tf=Tfo-Δ Tf =0-0.93= -0.93oC

Q. 0.5 molal solution of ethylene glycol in water is used as a coolant in car. If the freezing point depression constant of water is $1.8 6^{o} C k g$ per mole, the mixture will freeze at

$0.9 3^{o} C$

$- 0.9 3^{o} C$

$1.8 6^{o} C$

$- 1.8 6^{o} C$

$Δ T_{f} = k_{f} \times m$
$= 1.86 \times 0.5 = 0.9 3^{o} C$
$∴ Δ T_{f} = T_{f}^{o} - T_{f}$
$∴ T_{f} = T_{f}^{o} - Δ T_{f}$
$= 0 - 0.93 = - 0.9 3^{o} C$

Q. 0.5 molal solution of ethylene glycol in water is used as a coolant in car. If the freezing point depression constant of water is 1.86oCkg per mole, the mixture will freeze at

0.93oC

−0.93oC

1.86oC

−1.86oC