Question

What mass of ethlene ethyelne glycol `("molar mass"=62 g mol^(-1))` must be dissolved in 5.5kg of water to lower the freezing point of from `0^(@)C to-10^(@)C` ? `(K_(f))` for water=1.86 K kg `mol^(-1)`).

Answer 1

`M_(B)-(K_(f)xxW_(B))/(DeltaT_(f)xxW_(A))`
`DeltaT_(f)=(0-(-10))^(@)C=10K,K_(f)=1.86 K kg mol^(-1)`
`W_(A)=5.5 kg, M_(B)=62 g mol^(-1)`
`(62g mol^(-1))=((1.86 " K kg mol"^(-1))xxW_(B))/((10K)xx(5.5 kg))`
`W_(B)=((62gkm mol^(-1))xx(10K)xx(5.5kg))/((1.86 K kg mol^(-1)))=1833.3 g`