Textbook Question
Determine the formula weights of each of the following compounds: e. benzaldehyde, C6H5CHO, the molecule largely responsible for the odor of almond extract.
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Ch.3 - Chemical Reactions and Reaction Stoichiometry
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement111
- Ch.2 - Atoms, Molecules, and Ions166
- Ch.3 - Chemical Reactions and Reaction Stoichiometry138
- Ch.4 - Reactions in Aqueous Solution127
- Ch.5 - Thermochemistry104
- Ch.6 - Electronic Structure of Atoms109
- Ch.7 - Periodic Properties of the Elements107
- Ch.8 - Basic Concepts of Chemical Bonding102
- Ch.9 - Molecular Geometry and Bonding Theories120
- Ch.10 - Gases122
- Ch.11 - Liquids and Intermolecular Forces79
- Ch.12 - Solids and Modern Materials102
- Ch.13 - Properties of Solutions99
- Ch.14 - Chemical Kinetics153
- Ch.15 - Chemical Equilibrium83
- Ch.16 - Acid-Base Equilibria109
- Ch.17 - Additional Aspects of Aqueous Equilibria117
- Ch.18 - Chemistry of the Environment60
- Ch.19 - Chemical Thermodynamics109
- Ch.20 - Electrochemistry113
- Ch.21 - Nuclear Chemistry79
- Ch.22 - Chemistry of the Nonmetals52
- Ch.23 - Transition Metals and Coordination Chemistry57
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry7
Brown15th EditionChemistry: The Central ScienceISBN: 9780137542970Not the one you use?Change textbook
Chapter 3, Problem 26a
Calculate the percentage by mass of the indicated element in the following compounds: a. carbon in acetylene, C2H2, a gas used in welding
Verified step by step guidance1
Determine the molar mass of acetylene (C2H2). This involves adding the atomic masses of all the atoms in the molecule. Carbon has an atomic mass of approximately 12.01 g/mol and hydrogen has an atomic mass of approximately 1.008 g/mol. The formula for acetylene is C2H2, so the molar mass is calculated as follows: (2 \(\times\) 12.01 \(\text{ g/mol}\)) + (2 \(\times\) 1.008 \(\text{ g/mol}\)).
Calculate the total mass of carbon in one mole of acetylene. Since there are two carbon atoms in acetylene, multiply the atomic mass of carbon by 2.
To find the percentage by mass of carbon in acetylene, use the formula: \(\text{Percentage by mass} = \left(\frac{\text{mass of carbon in the compound}}{\text{molar mass of the compound}}\right) \times 100\%\).
Substitute the values obtained in the previous steps into the formula to calculate the percentage by mass of carbon.
Interpret the result to understand the contribution of carbon to the overall mass of acetylene and how it relates to the compound's chemical properties.
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Molar Mass
Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all the atoms in a molecule. For acetylene (C2H2), the molar mass is determined by adding the molar masses of two carbon atoms and two hydrogen atoms, which is essential for calculating the percentage by mass of carbon in the compound.
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Molar Mass Concept
Percentage by Mass
Percentage by mass is a way to express the concentration of an element in a compound, calculated by dividing the mass of the element by the total mass of the compound and multiplying by 100. This concept is crucial for understanding how much of a compound's mass is contributed by a specific element, such as carbon in acetylene, allowing for comparisons between different compounds.
Empirical Formula
The empirical formula represents the simplest whole-number ratio of the elements in a compound. In the case of acetylene (C2H2), the empirical formula indicates that for every two carbon atoms, there are two hydrogen atoms. Understanding the empirical formula is important for determining the composition of a compound and calculating the mass percentages of its constituent elements.
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