A `0.50` molal solution of ethylene glycol in water is used as coolant in a car . If the freezing point constant of water is `1.86^(@)` per molal , at which temperature will the mixture freeze?

Options

A. `0.93^(@)C`
B. `-0.93^(@)C`
C. `1.86^(@)C`
D. `-1.86^(@)C`

Answer

B

Explanation

`DeltaT_(f) = K_(f) xx m`
`= 1.86 xx 0.5 = 0.93^(@)`
`DeltaT_(f) = T_(b)^(@) - T_(b)`
`T_(b) = T_(b)^(@) - DeltaT_(f)`
`=0 - 0.93^(@) =- 0.93^(@)C`