Respuesta :
Answer:
Molecular formula = empirical formula = COCl2
Explanation:
Step 1: Data given
MAss of carbon = 0.305 grams
MAss of oxygen = 0.407 grams
Mass of chlorine = 1.805 grams
A different sample of the same gas having a mass of 8.84 g occupies 2 L at STP
Atomic mass of C = 12.01 g/mol
Molar mass of O2 = 16.0 g/mol
Molar mass of Cl2 = 35.45 g/mol
Step 2: Calculate moles
Moles = mass / molar mass
Moles C = 0.305 grams / 12.01 g/mol
Moles C = 0.0254 moles
Moles O = 0.407 grams / 16.0 g/mol
Moles O = 0.0254 moles
Moles Cl = 1.805 grams / 35.45 g/mol
Moles Cl = 0.0509 moles
Step 3: Calculate the mol ratio
We divide by the smallest amount of moles
C: 0.0254 moles / 0.0254 moles = 1
O: 0.0254 moles / 0.0254 moles = 1
Cl: 0.0509 / 0.0254 = 2
The empirical formula is COCl2
Step 4: Calculate moles
At STP we have 22.4 L for 1 mol
For 2 L we have 1 / 11.2 = 0.0893 moles
Step 5: Calculate the molar mass
Molar mass = mass / moles
Molar mass = 8.84 grams / 0.0893 moles
Molar mass = 98.99 g/mol
Step 6: Calculate the molar mass of the empirical formula
COCl2 = 12.01 + 16.0 + 70.9 ≠ 98.91 g/mol
Step 7: Calculate the molecular formula
Molecular formula = empirical formula = COCl2
The molecular formula of the compound containing 0.305 g of carbon, 0.407 g of oxygen and 1.805 g of chlorine is COCl₂
We'll begin by calculating the empirical formula of the compound. This can be obtained as follow:
C = 0.305 g
O = 0.407 g
Cl = 1.805 g
Divide by their molar mass
C = 0.305 / 12 = 0.0254
O = 0.407 / 16 = 0.0254
Cl = 1.805 / 35.5 = 0.0508
Divide by the smallest
C = 0.0254 / 0.0254 = 1
O = 0.0254 / 0.0254 = 1
Cl = 0.0508 / 0.0254 = 2
Thus, the empirical formula of the compound is COCl₂
Next, we shall determine the number of mole of the gas that occupies 2 L at STP.
At standard temperature and pressure (STP),
22.4 L = 1 mole
Therefore,
2 L = 2 / 22.4
2 L = 0.089 mole
Thus, the number of mole of the gas that occupied 2 L at STP is 0.089 mole.
Next, we shall determine the molar mass of the gas.
Mass of gas = 8.84 g
Mole of gas = 0.089 mole.
Molar mass of gas =?
Molar mass = mass / mole
Molar mass of gas = 8.84 / 0.089
Molar mass of gas = 99.3 g/mol
Finally, we shall determine the molecular formula of the compound. This can be obtained as follow:
Empirical formula = COCl₂
Molar mass = 99.3 g/mol
Molecular formula =?
Molecular formula = Empirical × n = molar mass
[COCl₂]n = 99.3
[12 + 16 + (2×35.5)]n = 99.3
99n = 99.3
Divide both side by 99
n = 99.3 / 99
n = 1
Molecular formula = [COCl₂]n
Molecular formula = [COCl₂] × 1
Molecular formula = COCl₂
Therefore, the molecular formula of the compound is COCl₂
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