Chemical analysis reveals capsaicin to contain 71.0% of carbon, 8.60% hydrogen, 15.8% oxygen and 4.60% nitrogen.

a) Determine the empirical formula of capsaicin
b) Each molecule contains one atom of nitrogen. What is the molecular formula of capsaicin?

I figured out the empirical formula but I got stuck on the molecular formula.

Well i found the moles of each element.

Carbon has 5.91mol
Hydrogen has 8.51mol
Oxygen has 0.988mol
Nitrogen has 0.328mol
Then I put the moles as subscripts and divded each subscript by the lowest amount of moles (nitrogen with 0.328mol). Then as the empirical formula I get C18H26O3N.

So in order to get the molecular formula, I need the actual mass of the molecular formula but I do not know how to find it. Because you have to divide the mass of the molecular formula by the mass of the empirical formula.

Your formula of C18H26O3N is correct. The last part is done with the Each molecule contains one atom of nitrogen. What is the molecular formula of capsaicin?

The catch is in the statement. If each molecule contains one atoms of N, then the empirical formula must be the same as the molecular formula for your empirical formula contains just 1 atom of N.

It will be easier to catch the error if you post what you have done.

Awesome! Thanks

marty you a real one i kno im from the future but let me tell u what i had a quiz on that exact question like bruh they still using questions from 2007 i was literally 2 years old at that time but d am who knew i was gonna answer this in 2022 u a real one fr fr

To determine the empirical formula of capsaicin, we need to find the simplest whole-number ratio of the atoms present in the compound.

a) Empirical formula calculation:

1. Convert the given percentages into masses:
Let's assume we have 100g of capsaicin.
Mass of carbon = 71.0g
Mass of hydrogen = 8.60g
Mass of oxygen = 15.8g
Mass of nitrogen = 4.60g

2. Convert the masses into moles:
Moles of carbon = 71.0g / atomic mass of carbon (12.01g/mol) = 5.912 moles
Moles of hydrogen = 8.60g / atomic mass of hydrogen (1.008g/mol) = 8.55 moles
Moles of oxygen = 15.8g / atomic mass of oxygen (16.00g/mol) = 0.9875 moles
Moles of nitrogen = 4.60g / atomic mass of nitrogen (14.01g/mol) = 0.328 moles

3. Divide each mole value by the smallest mole value:
Dividing all the mole values by 0.328 (the smallest mole value), we get:
Carbon: 5.912 moles / 0.328 moles = 18
Hydrogen: 8.55 moles / 0.328 moles ≈ 26
Oxygen: 0.9875 moles / 0.328 moles ≈ 3
Nitrogen: 0.328 moles / 0.328 moles = 1

The empirical formula of capsaicin is C18H26NO3.

b) Molecular formula calculation:

To determine the molecular formula, we need to know the molar mass of capsaicin. Let’s assume it is X g/mol.

1. Calculate the empirical formula's molar mass:
Molar mass of C18H26NO3 = (atomic mass of carbon x 18) + (atomic mass of hydrogen x 26) + (atomic mass of nitrogen x 1) + (atomic mass of oxygen x 3)

2. Compare the empirical formula's molar mass to the given molar mass (X g/mol):
If the given molecular mass (X) is a multiple of the empirical formula molar mass, then the molecular formula is a multiple of the empirical formula. If not, the molecular formula is the same as the empirical formula.

Therefore, you need to calculate the molar mass of the empirical formula (C18H26NO3). If it matches the molecular mass provided for capsaicin, the empirical and molecular formulas will be the same. If not, you need additional information (e.g., the molar mass of capsaicin) to determine the molecular formula.