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Ch.1 - Structure and Bonding
Wade - Organic Chemistry 9th Edition
Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook
All textbooksWade 9th EditionCh.1 - Structure and BondingProblem 48a
Chapter 1, Problem 48a

In 1934, Edward A. Doisy of Washington University extracted 3000 lb of hog ovaries to isolate a few milligrams of pure estradiol, a potent female hormone. Doisy burned 5.00 mg of this precious sample in oxygen and found that 14.54 mg of CO2 and 3.97 mg of H2O were generated.
a. Determine the empirical formula of estradiol.

Verified step by step guidance
1
Step 1: Begin by determining the moles of carbon in the sample. Use the mass of CO2 produced to find the moles of carbon. The molecular weight of CO2 is approximately 44.01 g/mol, and it contains one mole of carbon per mole of CO2. Calculate the moles of CO2 using the formula: \( \text{moles of CO2} = \frac{14.54 \text{ mg}}{44.01 \text{ g/mol}} \). Then, convert mg to g by dividing by 1000.
Step 2: Calculate the moles of hydrogen in the sample using the mass of H2O produced. The molecular weight of H2O is approximately 18.02 g/mol, and it contains two moles of hydrogen per mole of H2O. Calculate the moles of H2O using the formula: \( \text{moles of H2O} = \frac{3.97 \text{ mg}}{18.02 \text{ g/mol}} \). Convert mg to g by dividing by 1000, and then multiply by 2 to find the moles of hydrogen.
Step 3: Determine the moles of oxygen in the sample. Since the sample was burned in oxygen, the oxygen in the CO2 and H2O comes from both the estradiol and the oxygen used in combustion. Use the moles of carbon and hydrogen calculated in steps 1 and 2 to find the moles of oxygen in the estradiol. Subtract the moles of oxygen in CO2 and H2O from the total moles of oxygen used.
Step 4: Calculate the mole ratio of carbon, hydrogen, and oxygen. Divide the moles of each element by the smallest number of moles calculated in steps 1, 2, and 3 to find the simplest whole number ratio. This ratio will give you the empirical formula of estradiol.
Step 5: Write the empirical formula using the mole ratios obtained in step 4. The empirical formula is the simplest formula that represents the ratio of elements in the compound. Ensure that the subscripts in the formula are whole numbers.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Empirical Formula

The empirical formula of a compound represents the simplest whole-number ratio of the elements present in the compound. It is determined by converting the mass of each element to moles and then dividing by the smallest number of moles to find the ratio. This formula does not necessarily reflect the actual number of atoms in a molecule but provides the simplest representation of its composition.
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Combustion Analysis

Combustion analysis is a method used to determine the elemental composition of a compound, particularly organic compounds. In this process, a sample is burned in excess oxygen, and the amounts of carbon dioxide and water produced are measured. These measurements allow for the calculation of the amounts of carbon and hydrogen in the original sample, which are essential for determining the empirical formula.
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Mole Concept

The mole is a fundamental unit in chemistry that represents a specific number of particles, usually atoms or molecules, equivalent to Avogadro's number (6.022 x 10^23). It allows chemists to convert between the mass of a substance and the number of atoms or molecules it contains. Understanding the mole concept is crucial for converting the mass of elements obtained from combustion analysis into moles, which is necessary for determining the empirical formula.
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Related Practice
Textbook Question

Compound X, isolated from lanolin (sheep's wool fat), has the pungent aroma of dirty sweatsocks. A careful analysis showed that compound X contains 62.0% carbon and 10.4% hydrogen. No nitrogen or halogen was found.

b. A molecular weight determination showed that compound X has a molecular weight of approximately 117. Find the molecular formula of compound X.

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Textbook Question

In 1934, Edward A. Doisy of Washington University extracted 3000 lb of hog ovaries to isolate a few milligrams of pure estradiol, a potent female hormone. Doisy burned 5.00 mg of this precious sample in oxygen and found that 14.54 mg of CO2 and 3.97 mg of H2O were generated.

b. The molecular weight of estradiol was later determined to be 272. Determine the molecular formula of estradiol.

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Textbook Question

Compound X, isolated from lanolin (sheep’s wool fat), has the pungent aroma of dirty sweatsocks. A careful analysis showed that compound X contains 62.0% carbon and 10.4% hydrogen. No nitrogen or halogen was found.

a. Compute an empirical formula for compound X

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Textbook Question

Cyclopropane (C3H6, a three-membered ring) is more reactive than most other cycloalkanes.

a. Draw a Lewis structure for cyclopropane.

b. Compare the bond angles of the carbon atoms in cyclopropane with those in an acyclic (noncyclic) alkane.

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Textbook Question

Use resonance structures to identify the areas of high and low electron density in the following compounds:

i.

j.

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Textbook Question

If the carbon atom in CH2Cl2 were flat, there would be two stereoisomers. The carbon atom in CH2Cl2 is actually tetrahedral. Make a model of this compound, and determine whether there are any stereoisomers of CH2Cl2. 

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