Final answer:
The percent composition of codeine (C₁₈H₂₁NO₃), one must calculate the molar mass of codeine and then figure out the contribution of each element to this molar mass. The percent compositions are 72.24% carbon, 7.02% hydrogen, 4.68% nitrogen, and 16.05% oxygen.
Step-by-step explanation:
The student has asked the question: What is the percent composition of codeine (C₁₈H₂₁NO₃)? To calculate the percent composition of codeine, we must first determine the molar mass of codeine by summing the atomic masses of each element multiplied by the number of atoms of that element in the molecule.
The atomic masses for carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) are roughly 12, 1, 14, and 16 g/mol, respectively. For codeine (C₁₈H₂₁NO₃), the molar mass is calculated as follows:
- Carbon: 18 atoms × 12 g/mol = 216 g/mol
- Hydrogen: 21 atoms × 1 g/mol = 21 g/mol
- Nitrogen: 1 atom × 14 g/mol = 14 g/mol
- Oxygen: 3 atoms × 16 g/mol = 48 g/mol
Adding these together, the molar mass of codeine is 216 + 21 + 14 + 48 = 299 g/mol.
To find the percent composition, we divide the mass of each element in one mole of codeine by the molar mass of codeine and then multiply by 100:
- Percent composition of Carbon: (216 g/mol / 299 g/mol) × 100 = 72.24%
- Percent composition of Hydrogen: (21 g/mol / 299 g/mol) × 100 = 7.02%
- Percent composition of Nitrogen: (14 g/mol / 299 g/mol) × 100 = 4.68%
- Percent composition of Oxygen: (48 g/mol / 299 g/mol) × 100 = 16.05%
Therefore, the percent compositions of codeine are as follows: 72.24% C, 7.02% H, 4.68% N, and 16.05% O.