Answer :
Using the Dumas method, the molar mass of the volatile liquid is calculated by first working out the mass of the vapor, finding the volume of the flask using the density of water, and then, after converting temperature to Kelvin and pressure to atm, inserting these values into the formula. The calculated molar mass comes out to be 46.7 g/mol.
In the Dumas method, the molar mass of a volatile liquid can be calculated using the following formula:
Molar Mass = (mass of vapor / volume of flask) * (RT/P)
First, let's calculate the mass of the vapor. This is done by subtracting the mass of the empty flask from the mass of the flask with the condensed liquid (65.739 g - 65.347 g = 0.392 g).
Then, to find the volume of the flask, we'll use the density of water and the mass of the flask filled with water.
Since density = mass/volume, then volume = mass/density.
In this case, volume = (327.4 g - 65.347 g) / 0.997 g/mL
= 262.372 mL
= 0.262372 L.
Finally, we convert the temperature in Celsius to Kelvin by adding 273.15 to the measured temperature (99.8°C + 273.15 = 372.95 K), and the atmospheric pressure from Torr to atm by dividing by 760 (743.3 Torr / 760 = 0.978289 atm).
Plugging these values into the formula, we can calculate the molar mass, which comes out to be 46.7 g/mol.
Learn more about Dumas method here:
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