**Step 1: **49.5% C, 5.15% H, 28.9% N, and 16.5% O by mass.** **Recall that ** mass percent** is given by:

$\overline{){\mathbf{\%}}{\mathbf{}}{\mathbf{mass}}{\mathbf{=}}\frac{\mathbf{mass}\mathbf{}\mathbf{of}\mathbf{}\mathbf{X}}{\mathbf{total}\mathbf{}\mathbf{mass}}{\mathbf{\times}}{\mathbf{100}}}$

Assuming we have **100 g** of the compound, this means we have **49.5 g C, 5.15 g H, 28.9 g N, and 16.5 g O**.

Determine the empirical and molecular formulas of each of the following substances.

Caffeine, a stimulant found in coffee, contains 49.5% C, 5.15% H, 28.9% N, and 16.5% O by mass and has a molar mass of 195 g/mol.

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