I spent half an hr on this question - it doesn't make sense, its saying that water is solute, not solvent...Its due in half an hour!!!!!! PLEASE HELP!
What is the vapor pressure of the solvent in an aqueous solution at 25◦C of 0.29 m urea
(CO(NH2)2), a nonelectrolyte? The vapor pressure of water at 25◦C is 23.76 Torr.
Answer in units of Torr.
I know you use Psolution=XsolventPsolvent, and molality is number of moles/kg of solvent
To solve this problem, you can use Raoult's Law, which states that the vapor pressure of a solvent in a solution is equal to the vapor pressure of the pure solvent multiplied by the mole fraction of the solvent in the solution.
Mole fraction (Xsolvent) is the ratio of moles of solute to the total moles present in the solution. In this case, urea is the solute.
First, we need to find the mole fraction of the solvent (water). Since urea is a nonelectrolyte, it will not dissociate into ions. Therefore, the moles of solute (urea) and moles of solvent (water) will be the same.
Given:
Mole fraction of solute (urea) = 0.29
To find the mole fraction of the solvent (water), use the equation:
Mole fraction of solvent (water) = 1 - Mole fraction of solute (urea)
Mole fraction of solvent (water) = 1 - 0.29
Now that we have the mole fraction of the solvent (water), we can calculate the vapor pressure of the solvent using Raoult's Law:
Vapor pressure of solvent = Mole fraction of solvent (water) × Vapor pressure of pure solvent
Vapor pressure of solvent = (1 - 0.29) × 23.76 Torr
Calculate the value to find the vapor pressure of the solvent.
I understand that you're confused about this question and need help with it. Let's break it down step-by-step to make it clearer.
First, let's identify the solvent and solute in the given solution. In this case, the solvent is water (H2O) and the solute is urea (CO(NH2)2).
Next, we need to find the molality of the urea solution. Molality (m) is defined as the number of moles of solute per kilogram of solvent. The concentration of the urea solution is given as 0.29 m, which means there are 0.29 moles of urea dissolved in 1 kilogram of water.
Now, we can use the formula for Raoult's law to calculate the vapor pressure of the solvent in the solution. The formula is given as Psolution = Xsolvent * Psolvent, where Psolution is the vapor pressure of the solution, Xsolvent is the mole fraction of the solvent, and Psolvent is the vapor pressure of the pure solvent.
To find Xsolvent, we need to calculate the mole fraction of the solvent in the solution. The mole fraction (X) is defined as the moles of a component divided by the total moles of all components in the solution. Since we only have one solute and one solvent, the total moles is simply the moles of the solute.
To calculate Xsolvent, we can use the equation Xsolvent = moles of solvent / total moles. In this case, the total moles are equal to the moles of the solute (urea) since it's a nonelectrolyte. Thus, Xsolvent = moles of water / moles of urea.
Since we are given the molality of the solution and the molar mass of urea, we can calculate the moles of urea using the equation:
moles of urea = molality * mass of water / molar mass of urea.
Using the given molality of 0.29 m and the molar mass of urea, you can calculate the moles of urea.
Once you have the moles of urea, you can calculate the moles of water by subtracting it from the total mass of the solution (1 kilogram).
Finally, you can substitute the values into the equation Xsolvent = moles of water / moles of urea to find the mole fraction of the solvent.
Once you have the mole fraction of the solvent, you can multiply it by the vapor pressure of the pure solvent (given as 23.76 Torr) to get the vapor pressure of the solvent in the urea solution.
I hope this explanation helps you understand how to approach the problem. If you have any further questions, please let me know.