Textbook Question
Compute the empirical and molecular formulas for each of the following elemental analyses. In each case, propose at least one structure that fits the molecular formula.
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Ch.1 - Structure and Bonding
Wade9th EditionOrganic ChemistryISBN: 9780135213728
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Table of contents
- Ch.1 - Structure and Bonding107
- Ch. 2 - Acids and Bases; Functional Groups115
- Ch.3 - Structure and Stereochemistry of Alkanes100
- Ch.4 - The Study of Chemical Reactions99
- Ch.5 - Stereochemistry93
- Ch.6 - Alkyl Halides; Nucleophilic Substitution118
- Ch. 7 - Structure and Synthesis of Alkenes; Elimination158
- Ch.8 - Reactions of Alkenes171
- Ch.9 - Alkynes91
- Ch.10 - Structure and Synthesis of Alcohols143
- Ch.11 - Reactions of Alcohols104
- Ch. 12 - Infrared Spectroscopy and Mass Spectrometry22
- Ch. 13 - Nuclear Magnetic Resonance Spectroscopy45
- Ch. 14 - Ethers, Epoxides, and Thioethers72
- Ch. 15 - Conjugated Systems, Orbital Symmetry, and Ultraviolet Spectroscopy89
- Ch. 16 - Aromatic Compounds74
- Ch. 17 - Reactions of Aromatic Compounds126
- Ch. 18 - Ketones and Aldehydes193
- Ch. 19 - Amines129
- Ch. 20 - Carboxylic Acids77
- Ch. 21 - Carboxylic Acid Derivatives141
- Ch. 22 - Condensations and Alpha Substitutions of Carbonyl Compounds175
- Ch. 23 - Carbohydrates and Nucleic Acids93
- Ch. 24 - Amino Acids, Peptides, and Proteins54
Chapter 1, Problem 14d
Compute the empirical and molecular formulas for each of the following elemental analyses. In each case, propose at least one structure that fits the molecular formula.
Verified step by step guidance1
Convert the percentage composition of each element to grams, assuming a 100 g sample. This gives 38.4 g of C, 4.8 g of H, and 56.8 g of Cl.
Convert the mass of each element to moles by dividing by their respective atomic masses: C (12.01 g/mol), H (1.008 g/mol), and Cl (35.45 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.
Use the whole number ratio to write the empirical formula of the compound.
Calculate the molecular formula by comparing the empirical formula mass to the given molecular weight (125 g/mol) and multiplying the subscripts in the empirical formula by the appropriate factor.
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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 represents the simplest whole-number ratio of atoms of each element in a compound. It is derived from the elemental analysis data, which provides the mass percentages of each element present. For example, if a compound contains 40% carbon and 60% oxygen, the empirical formula can be determined by converting these percentages to moles and simplifying the ratio.
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Molecular Formula
The molecular formula indicates the actual number of atoms of each element in a molecule of a compound. It can be derived from the empirical formula by multiplying the subscripts by a whole number, known as the molecular weight factor. For instance, if the empirical formula is CH2 and the molecular weight is 28 g/mol, the molecular formula would be C2H4, as it corresponds to a molecular weight of 28 g/mol.
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Structural Representation
Structural representation involves depicting the arrangement of atoms within a molecule, which can be illustrated through various formats such as Lewis structures, condensed formulas, or skeletal structures. This representation is crucial for understanding the chemical behavior and properties of the compound. For example, knowing the molecular formula C2H4 allows for the proposal of structures like ethylene, which has a double bond between the carbon atoms.
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Related Practice
Textbook Question
Compute the empirical and molecular formulas for each of the following elemental analyses. In each case, propose at least one structure that fits the molecular formula.
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Textbook Question
The electrostatic potential maps for ammonia and water are shown here. The structure of ammonia is shown within its EPM. Note how the lone pair creates a region of high electron potential (red), and the hydrogens are in regions of low electron potential (blue). Show how your three-dimensional structure of water corresponds with its EPM.
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Textbook Question
Compute the empirical and molecular formulas for each of the following elemental analyses. In each case, propose at least one structure that fits the molecular formula.
3
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Textbook Question
Make a model of propane (C3H8), and draw this model using dashed lines and wedges to represent bonds going back and coming forward.
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Textbook Question
Predict the hybridization of the oxygen atom in water, H2O. Draw a picture of its three-dimensional structure, and explain why its bond angle is 104.5°.
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