Table of contents

1. Matter and Measurements4h 31m
2. Atoms and the Periodic Table5h 23m
3. Ionic Compounds2h 18m
4. Molecular Compounds2h 18m
5. Classification & Balancing of Chemical Reactions3h 17m
6. Chemical Reactions & Quantities2h 27m
7. Energy, Rate and Equilibrium3h 46m
8. Gases, Liquids and Solids3h 25m
9. Solutions4h 10m
10. Acids and Bases3h 29m
11. Nuclear Chemistry56m
BONUS: Lab Techniques and Procedures1h 38m
BONUS: Mathematical Operations and Functions47m
12. Introduction to Organic Chemistry1h 34m
13. Alkenes, Alkynes, and Aromatic Compounds2h 12m
14. Compounds with Oxygen or Sulfur1h 6m
15. Aldehydes and Ketones1h 1m
16. Carboxylic Acids and Their Derivatives1h 11m
17. Amines39m
18. Amino Acids and Proteins1h 51m
19. Enzymes1h 37m
20. Carbohydrates1h 41m
21. The Generation of Biochemical Energy2h 8m
22. Carbohydrate Metabolism2h 22m
23. Lipids2h 26m
24. Lipid Metabolism1h 45m
25. Protein and Amino Acid Metabolism1h 37m
26. Nucleic Acids and Protein Synthesis2h 54m

6. Chemical Reactions & Quantities

Molecular Formula

GOB Chemistry

6. Chemical Reactions & Quantities

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 percentage of oxygen in the compound by subtracting the percentages of carbon and hydrogen from 100%.

Convert the percentages of each element to grams, assuming you have 100 grams of the compound. This means you have 72.2 grams of carbon, 8.50 grams of hydrogen, and the remainder in grams of oxygen.

Convert the mass of each element to moles by dividing by their respective atomic masses: Carbon (C) is approximately 12.01 g/mol, Hydrogen (H) is approximately 1.008 g/mol, and Oxygen (O) is approximately 16.00 g/mol.

Determine the simplest whole number ratio of moles of each element by dividing each by the smallest number of moles calculated in the previous step. This gives you the empirical formula.

Calculate the molar mass of the empirical formula and compare it to the molar mass of the compound (41.55 g / 0.250 moles). Use this ratio to determine the molecular formula by multiplying the subscripts in the empirical formula by this ratio.