in a lab experiment to obtain the molar mass of a voltaile liquid, the following data is obtained:

volume of flask=225ml
mass of flask=77.834gms
mass of flask+gas=78.416gms
temperature=100 degrees celsius
pressure=714 torr

What is the molar mass of the liquid?

A)11.1 g/mol
B)22.6 g/mol
C)84.3 g/mol
D)99.2 g/mol

please help with working out this problem.

Use PV = nRT

Calculate n = number of moles of gas.

Then mols = g/molar mass
You know moles from the above calculation, you know grams (flask + gas - flask), solve for molar mass.

wow

didnt think of it that way.
thanks a lot
=)

To find the molar mass of the volatile liquid, we can use the ideal gas law equation, which relates the pressure, volume, temperature, and molar mass of a gas.

The ideal gas law equation is as follows:

PV = nRT

Where:
P = pressure (in atm or torr)
V = volume (in liters)
n = moles
R = ideal gas constant (0.0821 L.atm/(mol.K) for atm or 62.36 torr.L/(mol.K) for torr)
T = temperature (in Kelvin)

First, let's convert the given temperature from Celsius to Kelvin:

T(Kelvin) = T(Celsius) + 273.15
T(Kelvin) = 100 + 273.15
T(Kelvin) = 373.15 K

Now, let's convert the given volume from mL to L:

V(Liters) = V(mL) / 1000
V(Liters) = 225 mL / 1000
V(Liters) = 0.225 L

Next, let's calculate the moles of gas using the ideal gas law:

PV = nRT

n = (PV) / (RT)

First, let's convert the given pressure from torr to atm:

P(atm) = P(torr) / 760
P(atm) = 714 torr / 760
P(atm) = 0.9395 atm

Now, let's substitute the values into the equation:

n = (0.9395 atm * 0.225 L) / (0.0821 L.atm/(mol.K) * 373.15 K)

Simplifying the equation:

n = 0.0948 mol

The moles (n) of the gas are 0.0948 mol.

Finally, let's calculate the molar mass of the liquid using the formula:

Molar mass (g/mol) = Mass of flask + gas (g) - Mass of flask (g) / Moles of gas (mol)

Molar mass (g/mol) = 78.416 g - 77.834 g / 0.0948 mol

Molar mass (g/mol) ≈ 6.15 g/mol

The molar mass of the liquid is approximately 6.15 g/mol.

None of the given answer choices (A, B, C, D) match the calculated molar mass. It's possible there was an error in the calculations or the given answer choices are not accurate.