What Is the Boiling Point of a Urea Solution?

[sweetshelly]

Homework Statement

Calculate the boiling point (in degrees C) of a solution made by dissolving 7.49 g of urea {CO(NH2)2} in 28.0 g of water. The Kbp of the solvent is 0.512 K/m and the normal boiling point is 373 K

Homework Equations

Delta Tf = (i)(m)(Kbp)

The Attempt at a Solution

Kbp= 0.512 k/m

molality (m)= ?
first I have to find molality
(7.49g/60g)/(.028 kg water) = 4.458m

I don't know what the i value is. What do I do with the normal boiling point?

The answer is 102.283 celicus this would be 375.28K.
Then I did some research on the internet I came across this site that didn't use the i value is this possible.
375.28= 373 + delta Tf

 

[axewater]

I came to this forum to try and help out, but I see only so much stuff I don't know anything about anymore ... Obviously my education outdated LOL
I've reached my bioling point ... I'm going out for a smoke !

 

[Blueshift5]

delta Tf= 2.28 I would like to first clarify the question being asked. The boiling point of a solution is defined as the temperature at which the vapor pressure of the solution equals the external pressure. In this case, we are given the normal boiling point of water (373 K) and the boiling point elevation constant (Kbp) for water (0.512 K/m). We are also given the mass of solute (7.49 g) and the mass of solvent (28.0 g). The question asks for the boiling point of the solution (in degrees Celsius).

To solve this problem, we can use the equation Delta Tf = (i)(m)(Kbp), where Delta Tf is the boiling point elevation, i is the van't Hoff factor, m is the molality of the solution, and Kbp is the boiling point elevation constant.

First, we need to find the molality (m) of the solution. This can be calculated using the formula m = moles of solute / mass of solvent. In this case, the moles of urea can be calculated by dividing the mass of urea (7.49 g) by its molar mass (60 g/mol). This gives us 0.125 mol of urea. The mass of solvent (water) is given as 28.0 g. Thus, the molality of the solution is (0.125 mol / 0.028 kg) = 4.46 m.

Next, we need to find the van't Hoff factor (i). This factor takes into account the dissociation of solute particles in the solution. For a non-electrolyte like urea, the van't Hoff factor is 1. Therefore, we can substitute i = 1 in the equation.

Finally, we can plug in the values for Delta Tf, i, and m in the equation and solve for the boiling point elevation (Delta Tf). This gives us Delta Tf = (1)(4.46 m)(0.512 K/m) = 2.28 K.

The boiling point of the solution can be calculated by adding the boiling point elevation (2.28 K) to the normal boiling point of water (373 K). This gives us a boiling point of 375.28 K or 102.28 degrees Celsius.

In conclusion, as a scientist, I would approach this problem by first understanding the question being