Caffeine has the molecular formula, C8H10N4O2. What is the percent composition of c...

1. Identify the molecular formula: The molecular formula for caffeine is given as $C_8H_{10}N_4O_2$. This means one molecule of caffeine contains 8 carbon atoms, 10 hydrogen atoms, 4 nitrogen atoms, and 2 oxygen atoms.

2. Find the atomic masses of each element: We need the approximate atomic masses of carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) from the periodic table.
- Atomic mass of C = 12.01 g/mol
- Atomic mass of H = 1.01 g/mol
- Atomic mass of N = 14.01 g/mol
- Atomic mass of O = 16.00 g/mol

3. Calculate the molar mass of caffeine: The molar mass of caffeine is the sum of the atomic masses of all atoms in the molecule.
- Mass of C = $8 \times 12.01 = 96.08$ g/mol
- Mass of H = $10 \times 1.01 = 10.10$ g/mol
- Mass of N = $4 \times 14.01 = 56.04$ g/mol
- Mass of O = $2 \times 16.00 = 32.00$ g/mol
- Molar mass of caffeine = $96.08 + 10.10 + 56.04 + 32.00 = 194.22$ g/mol

4. Calculate the percent composition of each element: The percent composition of an element in a compound is calculated using the formula:
Percent composition = (Mass of element in compound / Molar mass of compound) $\times$ 100%

• Percent composition of C = $(96.08 / 194.22) \times 100\% \approx 49.47\%$
• Percent composition of H = $(10.10 / 194.22) \times 100\% \approx 5.20\%$
• Percent composition of N = $(56.04 / 194.22) \times 100\% \approx 28.85\%$
• Percent composition of O = $(32.00 / 194.22) \times 100\% \approx 16.48\%$

1. Compare with the given options: The calculated percentages are approximately 49.47% C, 5.20% H, 28.85% N, and 16.48% O. This closely matches the first option.