Answer to Question #268811 in General Chemistry for leo

Question

some ethylene glycol is added to your car's cooling system along with 5.0 kg. of water. If the freezing point of the water glycol solution is -15.0 degree celsius what mass of HOCH2CH2OH must have been added?

Answer 1

Taking K_f of water as $=1.86K\>kgmol^{-1}$

$-\Delta\>T_f=K_f×M$

$0-(-15)=1.86×M$

$M=\frac{15}{1.86}=8.0645\>moles$

Molar mass of ethylene glycol

= 62g

Mass added in 5kg of water

=8.0645×62×5

=2499.995g

=2.5kg