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

Cortisol (MW = 362.47 g/mol), a known steroid hormone, is found to contain 69.6% carbon, 8.34% hydrogen, and 22.1% oxygen by mass. What is its molecular formula?

C₂₁H₃₀O₅

C₂₁H₂₆O₅

C₂₈H₄₆O

C₁₈H₂₄O₂

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Verified step by step guidance

Step 1: Determine the mass of each element in 100 g of cortisol. Since the percentages are given, assume you have 100 g of the compound. This means you have 69.6 g of carbon, 8.34 g of hydrogen, and 22.1 g of oxygen.

Step 2: Convert the mass of each element to moles using their respective molar masses. Use the molar mass of carbon (12.01 g/mol), hydrogen (1.008 g/mol), and oxygen (16.00 g/mol) to find the moles of each element.

Step 3: Calculate the mole ratio of the elements by dividing the number of moles of each element by the smallest number of moles calculated in the previous step. This will give you the empirical formula.

Step 4: Determine the empirical formula mass by adding the atomic masses of the elements in the empirical formula.

Step 5: Divide the molecular weight of cortisol (362.47 g/mol) by the empirical formula mass to find the ratio. Multiply the subscripts in the empirical formula by this ratio to find the molecular formula.