Ok to answer this question we firsst need to fin the number of mol of Urea (CH4N2O). to do this we simply :
1 mol of urea =15/60.055 = 0.25mol
therefore 200g of water contain 0.25mol
the next step is to determine the malality of our solution in 200g of water, to do this we say:
200 g = 1Kg/1000g = 0.2kg
therefor 0.25mol/0.2Kg = 1.25mol/kg
and from the equation:
we know that i = 1
we are given Kf
b is the molality that we just calculated
therefore;
the solutions freezing point is -2.325°C
Answer:
0.13 m of → Highest boiling point
0.19 m of → Second Highest boiling point
0.17 m of → Third highest boiling point
0.31 m Sucrose (nonelectrolyte) → Lowest boiling point
Explanation:
Elevation in boiling is given by :
Where :
i = van't Hoff factor
= Molal Elevation constant of solvent
m = molaity of the solution
1) 0.19 m of
i = 2 (electrolyte)
Molality of the solution = 0.19
Elevation is boiling point of solution:
2) 0.17 m of
i = 2 (electrolyte)
Molality of the solution = 0.17
Elevation is boiling point solution :
3) 0.13 m of
i = 3 (electrolyte)
Molality of the solution = 0.13
Elevation is boiling point solution :
4) 0.31 m Sucrose (nonelectrolyte)
i = 1 ( non electrolyte)
Molality of the solution = 0.31 m
Elevation is boiling point solution :
Higher the value of elevation in temperature higher will be the boiling point of the solution .
The decreasing order of solution from highest boiling point to lowest boiling point is :
0.13 m of → Highest boiling point
0.19 m of → Second Highest boiling point
0.17 m of → Third highest boiling point
0.31 m Sucrose (nonelectrolyte) → Lowest boiling point