A liquid was analyzed to be 54.5% C, 9.10% H, and 36.4% O. An empty flask, whose mass was 45.32 g, when filled with the vapor of the liquid at 735mm Hg and 99.2°C had a mass of 46.05 g. The volume of the flask was found to be 263.2 mL.
empirical formula -> C2H4O
What is the molecular formula of the compound?
mass vapor = 46.05-45.32 = 0.73g
Use PV = nRT
Solve for n = number of mols
Then mol = grams/molar mass
You have grams and mol solve for molar mass.
molar mass/empirical mass = x. Round to whole number and
molecular formula = (C2H4O)*x
thank you so much!
To determine the molecular formula of the compound, we need to find the molar mass of the empirical formula (C2H4O) and compare it to the experimental molar mass.
1. Calculate the molar mass of the empirical formula:
Molar mass of carbon (C) = 12.01 g/mol
Molar mass of hydrogen (H) = 1.008 g/mol
Molar mass of oxygen (O) = 16.00 g/mol
Molar mass of C2H4O = (2 x 12.01) + (4 x 1.008) + 16.00 = 44.10 g/mol
2. Calculate the mass of the empirical formula in the experiment:
Mass of the flask filled with vapor = 46.05 g
Mass of the empty flask = 45.32 g
Mass of the vapor inside the flask = 46.05 g - 45.32 g = 0.73 g
3. Convert the mass of the empirical formula to moles:
Moles of C2H4O = Mass / Molar mass = 0.73 g / 44.10 g/mol ≈ 0.0166 mol
4. Determine the molar mass of the compound from the experimental data:
Molar mass of the compound = Mass / Moles = 0.73 g / 0.0166 mol ≈ 44.04 g/mol
5. Compare the molar mass of the compound to the molar mass of the empirical formula:
Molecular formula molar mass / Empirical formula molar mass = 44.04 g/mol / 44.10 g/mol ≈ 0.996
Since the ratio is close to 1, the empirical formula (C2H4O) is likely the same as the molecular formula of the compound. Therefore, the molecular formula of the compound is C2H4O.
To determine the molecular formula of the compound, we need to calculate its molar mass based on the given empirical formula and compare it to the experimental molar mass determined from the data provided.
1. Start by calculating the empirical formula mass:
- The molar mass of Carbon (C) is approximately 12 g/mol.
- The molar mass of Hydrogen (H) is approximately 1 g/mol.
- The molar mass of Oxygen (O) is approximately 16 g/mol.
Empirical formula mass = (2 * 12 g/mol) + (4 * 1 g/mol) + (1 * 16 g/mol) = 88 g/mol
2. Next, calculate the experimental molar mass:
- Subtract the mass of the empty flask (45.32 g) from the mass of the flask filled with the compound (46.05 g) to get the mass of the compound.
- Convert the mass of the compound to moles using the empirical formula mass.
Mass of the compound = 46.05 g - 45.32 g = 0.73 g
Moles of the compound = 0.73 g / 88 g/mol ≈ 0.0083 mol
3. Determine the number of empirical formula units in the molecular formula:
Since we know the empirical formula is C2H4O, the ratio of empirical formula units to molecular formula units is needed.
- Divide the molar mass of the compound by the empirical formula mass:
Molecular formula units = Experimental molar mass / Empirical formula mass
Molecular formula units = (0.73 g/mol) / (0.0083 mol) ≈ 88
The result indicates that the molecular formula has approximately 88 empirical formula units.
4. Finally, determine the molecular formula:
To determine the molecular formula, we need to find a whole number multiplier that gives the most appropriate number of empirical formula units while maintaining the empirical formula ratio. Divide the molecular formula units by the empirical formula ratio.
Number of empirical units in the molecular formula = 88
Empirical formula ratio = 1:1 (As C2H4O only has one carbon, one hydrogen, and one oxygen atom)
Molecular formula = (C2H4O) * (88 / 1) = C176H352O88
Therefore, the molecular formula of the compound is C176H352O88.