If vapour pressure of water is 17.5 torr at 20C, what is the water vapour pressure inside a bottle of 100 proof whiskey?
100 proof = 50% ethanol
Total volume = 1 L
Mass of ethanol = 394.5g
Mass of water = 500g
Density of ethanol = 0.789g/mL
Moles of ethanol = 8.58 mol
Moles of water = 27.75 mol
Molar concentration of ethanol = 17 molal
I am not sure. Can somebody please confirm
mol fraction of water : 27.75mol/36.3395mol = 0.76
mol fraction of ethanol : 8.5849 mol/36.3395 = 0.24
Vapour pressure of water inside a bottle of 100 proof : 13.3mmHg
(0.76)(17.5mmHg) = 13.3mmHg
Ptot = (0.76)(17.5mmHg) + (0.24)(44mmHg)
Ptot = 23.86mmHg
Has this answered been confirmed?
To determine the water vapor pressure inside a bottle of 100-proof whiskey, we need to calculate the mole fraction of water in the solution and use that information to find the partial pressure of water.
Step 1: Calculate the mole fraction of water:
Moles of water = mass of water / molar mass of water
Moles of water = 500 g / 18.015 g/mol = 27.75 mol
Moles of ethanol = mass of ethanol / molar mass of ethanol
Moles of ethanol = 394.5 g / 46.07 g/mol = 8.58 mol
Total moles = moles of water + moles of ethanol
Total moles = 27.75 mol + 8.58 mol = 36.33 mol
Mole fraction of water = moles of water / total moles
Mole fraction of water = 27.75 mol / 36.33 mol = 0.764
Step 2: Use the mole fraction of water to find the partial pressure of water:
Partial pressure of water = mole fraction of water * vapor pressure of water
Partial pressure of water = 0.764 * 17.5 torr = 13.37 torr
Therefore, the water vapor pressure inside the bottle of 100-proof whiskey would be approximately 13.37 torr.
To determine the water vapor pressure inside a bottle of 100 proof whiskey, we need to calculate the mole fraction of water in the solution and then use that value to find the partial pressure of water vapor.
First, calculate the total moles of solute (ethanol) and solvent (water) in the solution.
Moles of ethanol = mass of ethanol / molar mass of ethanol
Moles of ethanol = 394.5 g / (0.789 g/mL * 1000 mL/L * 46.07 g/mol)
Moles of ethanol ≈ 8.58 mol
Moles of water = mass of water / molar mass of water
Moles of water = 500 g / (1000 g/kg * 18.02 g/mol)
Moles of water ≈ 27.75 mol
Next, calculate the mole fraction of water in the solution.
Mole fraction of water = moles of water / (moles of ethanol + moles of water)
Mole fraction of water = 27.75 mol / (8.58 mol + 27.75 mol)
Mole fraction of water ≈ 0.763
Now, use the mole fraction of water to find the vapor pressure of water using Raoult's law.
Vapor pressure of water in the solution = mole fraction of water * vapor pressure of pure water
Vapor pressure of water in the solution = 0.763 * 17.5 torr
Vapor pressure of water in the solution ≈ 13.35 torr
Therefore, the water vapor pressure inside the bottle of 100 proof whiskey is approximately 13.35 torr.