Table of contents

1. The Chemical World9m
- The Scientific Method
  9m
2. Measurement and Problem Solving2h 19m
3. Matter and Energy2h 15m
4. Atoms and Elements2h 33m
5. Molecules and Compounds1h 50m
6. Chemical Composition1h 23m
7. Chemical Reactions1h 43m
8. Quantities in Chemical Reactions1h 8m
9. Electrons in Atoms and the Periodic Table2h 32m
10. Chemical Bonding2h 10m
11 Gases2h 7m
12. Liquids, Solids, and Intermolecular Forces1h 11m
13. Solutions3h 1m
14. Acids and Bases2h 14m
15. Chemical Equilibrium1h 27m
16. Oxidation and Reduction1h 33m
17. Radioactivity and Nuclear Chemistry53m

6. Chemical Composition

Molecular Formula

Introduction to Chemistry

6. Chemical Composition

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 19.3 g of O (since 100 - 72.2 - 8.50 = 19.3).

Convert the masses to moles using the molar masses of each element: 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. Calculate the moles for each element using the formula: \( \text{moles} = \frac{\text{mass}}{\text{molar mass}} \).

Divide the moles of each element by the smallest number of moles calculated in the previous step to find the simplest whole number ratio, which gives the empirical formula.

Calculate the molar mass of the empirical formula and compare it to the molar mass of the compound. The molar mass of the compound can be found by dividing the given mass (41.55 g) by the number of moles (0.250 moles), which gives the molar mass of the compound.

Determine the molecular formula by dividing the molar mass of the compound by the molar mass of the empirical formula. Multiply the subscripts in the empirical formula by this ratio to find the molecular formula.