A gas containing carbon and hydrogen analyzed as 85.6 % carbon and 14.4 % hydrogen. A 42.1 g sample of a gas occupied a volume of 7490 mL with a pressure of 2280.0 torr at 92 °C. Enter the molecular formula of the compound.

Thanks.

1. Take a 100 g sample. This will give you 85.6 g C and 14.4 g H.

Convert to mols, then find the ratio of the elements to each other with the smallest number being 1.00. This will give you the empirical formula.

2. Find the molar mass from
PV = nRT and solve for n = number of mols. Then n = grams/molar mass; you know n and grams, solve for molar mass.

3. empirical formula mass*x = molar mass. Then x is the subscript in this formula. (empirical formula)x
Post your work if you get stuck.

Got it. thanks for the help!

To determine the molecular formula of the compound, we need to calculate the empirical formula first, and then use the molar mass to find the molecular formula.

1. Calculate the empirical formula:
The percentages of carbon and hydrogen can be converted to moles using the masses from the analysis.

Given:
Mass of carbon = 85.6% of 42.1 g = 36.0096 g
Mass of hydrogen = 14.4% of 42.1 g = 6.0624 g

Now we need to convert the masses of carbon and hydrogen into moles.

First, find the molar mass of carbon (C) and hydrogen (H):
Molar mass of carbon (C) = 12.01 g/mol
Molar mass of hydrogen (H) = 1.008 g/mol

Next, convert the masses to moles:

Moles of carbon = Mass of carbon / Molar mass of carbon
Moles of carbon = 36.0096 g / 12.01 g/mol = 2.998 moles

Moles of hydrogen = Mass of hydrogen / Molar mass of hydrogen
Moles of hydrogen = 6.0624 g / 1.008 g/mol = 6.019 moles

Now we need to find the ratio between the moles of carbon and hydrogen by dividing both by the smaller value:

Moles of carbon (C) = 2.998 moles / 2.998 moles = 1 mole
Moles of hydrogen (H) = 6.019 moles / 2.998 moles ≈ 2 moles

Based on this ratio, the empirical formula is CH2.

2. Calculate the molar mass:
The molar mass of the empirical formula CH2 can be calculated as follows:

Molar mass of carbon (C) = 12.01 g/mol
Molar mass of hydrogen (H) = 1.008 g/mol

Molar mass of CH2 = (12.01 g/mol) + (2 * 1.008 g/mol)
Molar mass of CH2 = 12.01 g/mol + 2.016 g/mol
Molar mass of CH2 = 14.026 g/mol

3. Find the molecular formula:
The molar mass of the compound is given as 14.026 g/mol, and the molar mass of the empirical formula CH2 is 14.026 g/mol.

To find the molecular formula, we divide the molar mass of the compound by the molar mass of the empirical formula:

Molar mass of the compound / Molar mass of the empirical formula = 14.026 g/mol / 14.026 g/mol = 1

Since the result is 1, the empirical formula (CH2) is also the molecular formula.

Therefore, the molecular formula of the compound is CH2.