Textbook Question
What are the molecular and empirical formulas for each of the following compounds? Write the molecular formula for the following compound.
Ch.2 - Atoms, Molecules, and Ions
Chapter 2, Problem 49b
Write the empirical formula corresponding to each of the following molecular formulas: (b) C8H10
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Identify the greatest common divisor (GCD) of the subscripts in the molecular formula C_8H_{10}.
Divide each subscript in the molecular formula by the GCD to simplify the ratio of atoms.
For C_8H_{10}, the GCD of 8 and 10 is 2.
Divide the subscript of carbon (8) by 2 to get 4, and the subscript of hydrogen (10) by 2 to get 5.
The empirical formula is the simplest whole number ratio of atoms, which is C_4H_5.
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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 that compound. It does not provide information about the actual number of atoms in a molecule but rather the relative proportions of each element. For example, the empirical formula for glucose (C6H12O6) is CH2O, indicating a 1:2:1 ratio of carbon, hydrogen, and oxygen.
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02:26
Empirical vs Molecular Formula
Molecular Formula
The molecular formula of a compound indicates the actual number of atoms of each element in a molecule. It provides more specific information than the empirical formula and can be derived from it by multiplying the subscripts in the empirical formula by a whole number. For instance, the molecular formula C8H10 indicates that there are 8 carbon atoms and 10 hydrogen atoms in the molecule.
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02:08Determining Molecular Formulas
Dividing by the Greatest Common Factor
To derive the empirical formula from a molecular formula, one must divide the subscripts of the molecular formula by their greatest common factor (GCF). This process simplifies the ratio of the elements to its lowest terms. For the molecular formula C8H10, the GCF of 8 and 10 is 2, leading to the empirical formula C4H5.
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02:38Common Conversion Factors
Related Practice
Textbook Question
Two substances have the same molecular and empirical formulas. Does this mean that they must be the same compound?
Textbook Question
Write the empirical formula corresponding to each of the following molecular formulas: (a) Al2Br6
Textbook Question
Write the empirical formula corresponding to each of the following molecular formulas: (c) C4H8O2
Textbook Question
Write the empirical formula corresponding to each of the following molecular formulas: (d) P4O10 (e) C6H4Cl2 (f) B3N3H6.
Textbook Question
Determine the molecular and empirical formulas of the following: (a) the organic solvent benzene, which has six carbon atoms and six hydrogen atoms