glycerin C3H8O is a nonvolatile liquid. what is the vapor pressure of a solution made by adding 164 g of glycerin to 338 mL of H2O at 39.8C. The vapor pressure of pure water at 39.8C is 54.74 torr and its density is 0.992 g/cm3
P solution= X solvent p solvent
1.78g C3H8O3
Use density to calculate mass H2O.
mass = volume x density.
Calculate mole fraction H2O
n H2O = grams/molar mass
n glycerin = grams/molar mass
ntotal = n H2O + n glycerin
XH2O = n H2O/n total
psoln = XH2O*PoH2O
Post your work if you get stuck.
To find the vapor pressure of the solution, we need to calculate the mole fraction of the solvent (water) and then use it to determine the partial pressure of the solvent.
Step 1: Calculate the moles of water (solvent):
We are given the mass of water and its density. We can calculate the volume of water using its density:
Volume of water = 338 mL = 338 cm^3
Mass of water = Volume of water x Density of water
Mass of water = 338 cm^3 x 0.992 g/cm^3 = 334.496 g
Now, convert the mass of water to moles:
Molar mass of water (H2O) = 18.015 g/mol
Moles of water = Mass of water / Molar mass of water
Moles of water = 334.496 g / 18.015 g/mol ≈ 18.56 mol
Step 2: Calculate the moles of glycerin (solute):
We are given the mass of glycerin:
Moles of glycerin = Mass of glycerin / Molar mass of glycerin
Molar mass of glycerin (C3H8O3) = 92.093 g/mol
Moles of glycerin = 164 g / 92.093 g/mol ≈ 1.78 mol
Step 3: Calculate the mole fraction of the solvent:
Mole fraction of water (solvent) = Moles of water / (Moles of water + Moles of glycerin)
Mole fraction of water = 18.56 mol / (18.56 mol + 1.78 mol)
Mole fraction of water = 0.912
Step 4: Calculate the partial pressure of the solvent:
Partial pressure of water (solvent) = Mole fraction of water x Vapor pressure of pure water
Partial pressure of water = 0.912 x 54.74 torr
Partial pressure of water ≈ 49.94 torr
Therefore, the vapor pressure of the solution made by adding 164 g of glycerin to 338 mL of water at 39.8°C is approximately 49.94 torr.