THank you for help steve with the other one!! :)
My other one is:
The compostition of adipic acid used in the manufacture of Nylon is 49.3%c, 6.9% H and 43.89%O. The molecular mass is known to be 146 amu. What is the molecular formula of adipic acid?
I got C6-H10-O4. DID I DO THIS RIGHT?
To determine if you have correctly determined the molecular formula for adipic acid, we can calculate the empirical formula and compare it to the given molecular formula.
1. Start by assuming 100 grams of adipic acid. This allows us to convert the given percentages into grams.
- Carbon (C): 49.3% of 100 grams = 49.3 grams
- Hydrogen (H): 6.9% of 100 grams = 6.9 grams
- Oxygen (O): 43.89% of 100 grams = 43.89 grams
2. Convert the grams of each element to moles using their atomic masses (rounded to the nearest whole number):
- Carbon (C): 49.3 grams / 12.01 g/mol ≈ 4.1 moles
- Hydrogen (H): 6.9 grams / 1.01 g/mol ≈ 6.8 moles
- Oxygen (O): 43.89 grams / 16.00 g/mol ≈ 2.7 moles
3. Divide each mole value by the smallest mole value:
- Carbon (C): 4.1 moles / 2.7 moles ≈ 1.5
- Hydrogen (H): 6.8 moles / 2.7 moles ≈ 2.5
- Oxygen (O): 2.7 moles / 2.7 moles ≈ 1.0
4. The resulting mole ratios are approximately 1.5:2.5:1.0, which can be simplified to 3:5:2. Therefore, the empirical formula of adipic acid is C3H5O2.
5. To find the molecular formula, we divide the given molecular mass (146 amu) by the empirical formula mass (C3H5O2) which is calculated as follows:
- Carbon (C): 3 atoms × 12.01 g/mol = 36.03 g/mol
- Hydrogen (H): 5 atoms × 1.01 g/mol = 5.05 g/mol
- Oxygen (O): 2 atoms × 16.00 g/mol = 32.00 g/mol
- Empirical formula mass (C3H5O2) = 36.03 g/mol + 5.05 g/mol + 32.00 g/mol ≈ 73.08 g/mol
6. Molecular formula mass = (Empirical formula mass) × n, where n is the integer multiplier.
- 146 amu = 73.08 g/mol × n
- n ≈ 2
7. Multiply each atom in the empirical formula by the multiplier:
- Carbon: 3 atoms × 2 = 6 atoms → C6
- Hydrogen: 5 atoms × 2 = 10 atoms → H10
- Oxygen: 2 atoms × 2 = 4 atoms → O4
So, the correct molecular formula for adipic acid is C6H10O4, which matches the value you obtained. Well done!