InterviewSolution
Saved Bookmarks
| 1. |
How much ethly alcohol much be added ot 1.0 litre of water so that the solution may treeze at `-10^(@)C. (K_(f) "for water =1.88 K kg" mol^(-1), "density of water=1 g "mL^(-1)).` |
|
Answer» Correct Answer - 247.3g Step I. Calculation of molality of the solution. `DeltaT_(f)=K_(f)xxm` `DeltaT_(f)=0^(@)C-(-10^(@)C)=10^(@)C=10 K, K_(f)=1.86" K kg mol"^(-1)` `m=(DeltaT_(f))/K_(f)=((10K))/((1.86" K kg mol"^(-1)))=5.376" mol kg"^(-1)=5.376 m.` Step II. Calculation of amount of ethyl alcohol to be added. `"Molality (m)"=("Mass of ethyl alcohol / Molar mass")/("Mass of water / 1000")` `5.376" mol kg"^(-1)=(W_(B)//(46"g mol"^(-1)))/(1" kg")` `W_(B)=(5.376" mol kg"^(-1))xx(46" g mol"^(-1))xx(1 kg)=247.3 g.` |
|