Table of contents

1. Intro to General Chemistry3h 48m
2. Atoms & Elements4h 16m
3. Chemical Reactions4h 10m
4. BONUS: Lab Techniques and Procedures1h 38m
5. BONUS: Mathematical Operations and Functions48m
6. Chemical Quantities & Aqueous Reactions3h 53m
7. Gases3h 49m
8. Thermochemistry2h 37m
9. Quantum Mechanics2h 58m
10. Periodic Properties of the Elements3h 9m
11. Bonding & Molecular Structure3h 29m
12. Molecular Shapes & Valence Bond Theory1h 57m
13. Liquids, Solids & Intermolecular Forces2h 23m
14. Solutions3h 1m
15. Chemical Kinetics2h 53m
16. Chemical Equilibrium2h 29m
17. Acid and Base Equilibrium5h 1m
18. Aqueous Equilibrium4h 47m
19. Chemical Thermodynamics1h 50m
20. Electrochemistry2h 42m
21. Nuclear Chemistry2h 36m
22. Organic Chemistry5h 7m
23. Chemistry of the Nonmetals2h 39m
24. Transition Metals and Coordination Compounds3h 16m

3. Chemical Reactions

Molecular Formula

General Chemistry

3. Chemical Reactions

Molecular Formula

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Multiple Choice

Elemental analysis of a pure compound indicated that the compound had 72.2% C, 8.50% H and the remainder as O. If 0.250 moles of the compound weighs 41.55 g, what is the molecular formula of the compound?

C₅H₇O

C₁₀H₁₄O₂

C₆H₈O₂

C₁₂H₁₆O₄

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Verified step by step guidance

Determine the empirical formula by converting the percentage composition to moles. Assume 100 g of the compound, which gives 72.2 g of C, 8.50 g of H, and the remainder as O. Calculate the moles of each element using their atomic masses: C (12.01 g/mol), H (1.008 g/mol), and O (16.00 g/mol).

Calculate the moles of each element: \( \text{moles of C} = \frac{72.2}{12.01} \), \( \text{moles of H} = \frac{8.50}{1.008} \), \( \text{moles of O} = \frac{100 - 72.2 - 8.50}{16.00} \).

Determine the simplest whole number ratio of moles of C, H, and O by dividing each by the smallest number of moles calculated in the previous step.

Use the empirical formula to find the empirical formula mass. Then, calculate the molar mass of the compound using the given mass and moles: \( \text{molar mass} = \frac{41.55 \text{ g}}{0.250 \text{ moles}} \).

Determine the molecular formula by dividing the molar mass by the empirical formula mass to find the multiplier. Multiply the subscripts in the empirical formula by this number to get the molecular formula.