A 0.194 g sample of compound is vaporized to fill a 100.0 mL vessel at 750. torr and 100.C. What is the molar mass and molecular formula?
To find the molar mass and molecular formula of the compound, we need to use the ideal gas law and the concept of molar mass.
1. Start by converting the mass of the sample to moles. Use the molar mass as the conversion factor. The molar mass (M) is calculated using the formula:
M = (mass of sample in grams) / (moles of the sample)
2. Next, determine the number of moles of the gas using the ideal gas law equation:
PV = nRT
Where:
P = pressure (in atm) = 750. torr / 760 torr/atm
V = volume (in L) = 100.0 mL / 1000 mL/L
n = number of moles of gas
R = ideal gas constant = 0.0821 L.atm/(mol.K)
T = temperature (in Kelvin) = 100.C + 273.15
Solve the equation for n (number of moles of gas).
3. Divide the mass in moles from step 1 by the number of moles of the gas from step 2. This will give you the ratio of moles of the compound to moles of gas.
This ratio will be the subscript of the empirical formula.
4. Finally, determine the empirical formula by dividing each subscript by the greatest common divisor (GCD) to get the simplest whole number ratio.
The empirical formula is the simplest (most reduced) ratio of atoms in a compound.
Given the mass of the sample, pressure, volume, and temperature, you can perform these calculations to find the molar mass and molecular formula of the compound.