An empty flask weighs 128.632g. After vaporization of a sample of volatile liquid, at a measured temperature of 99.8 C. The flask is sealed, cooled to room temperature, and weighed. The mass is now 129.225g. The measured P atm is 757.7 torr. The flask is rinsed and filled completely with water at 21.8 C. The mass of the flask is now 381.676g.

1. Calculate the volume of the flask from the mass of the water contained in the flask and the density.

2. Calculate the molar mass of the volatile liquid.

Can you do #1? volume = mass/density

#2. Use PV = nRT and solve for n = number of mols.
Substitute into moles = grams/molar mass. You have grams (from the mass flask + vapor - mass empty flask) and moles. Solve for molar mass.

for #1, we have to find the density first right? so density is mass/volume, so from there you take 381.676 and divide that by..

and that's where im lost :(

Close but no cigar.

381.676 = mass flask + water
-128.632 = mass empty flask
---------
difference = mass water
volume of flask = mass water/density water = ??

sorry to be asking too much but how do we get the density of water?

To calculate the volume of the flask, we need to know the density of water at 21.8°C.

1. Calculate volume of the flask:
- Mass of water = mass of flask with water - mass of empty flask
Mass of water = 381.676g - 128.632g = 253.044g
- Density of water at 21.8°C = ρ (density) = 0.9982 g/mL (or 0.9982 g/cm³)
- Volume of water = Mass of water / Density of water
Volume of water = 253.044g / 0.9982 g/mL = 253.721 mL

Now, we have the volume of water in the flask, which is the same as the volume of the flask itself.

2. Calculate the molar mass of the volatile liquid:
- We can use the Ideal Gas Law equation: PV = nRT, where P is the pressure, V is the volume, n is the number of moles, R is the ideal gas constant, and T is the temperature in Kelvin.
- To use this equation, we need to convert the given pressure (757.7 torr) to atm and the temperature (99.8°C) to Kelvin.
P atm = 757.7 torr / 760 torr/atm = 0.995 atm
T K = 99.8°C + 273.15 = 373.95 K
- Rearranging the equation: n = (PV) / (RT)
n = (0.995 atm * 253.721 mL) / (0.0821 L·atm/(mol·K) * 373.95 K)
- Convert mL to L: 253.721 mL = 0.253721 L
n = (0.995 atm * 0.253721 L) / (0.0821 L·atm/(mol·K) * 373.95 K)
- Simplify: n = 0.0089729 mol
- Calculate the molar mass using the equation: Molar mass = mass / moles
Molar mass = (129.225g - 128.632g) / 0.0089729 mol
- Simplify: Molar mass = 67.214 g/mol

Therefore, the molar mass of the volatile liquid is approximately 67.214 g/mol.