Textbook Question
Determine the empirical formula of each of the following compounds if a sample contains (a) 3.92 mol C, 5.99 mol H, and 2.94 mol O
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Ch.3 - Chemical Reactions and Reaction Stoichiometry
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement140
- Ch.2 - Atoms, Molecules, and Ions192
- Ch.3 - Chemical Reactions and Reaction Stoichiometry172
- Ch.4 - Reactions in Aqueous Solution156
- Ch.5 - Thermochemistry151
- Ch.6 - Electronic Structure of Atoms137
- Ch.7 - Periodic Properties of the Elements127
- Ch.8 - Basic Concepts of Chemical Bonding143
- Ch.9 - Molecular Geometry and Bonding Theories167
- Ch.10 - Gases147
- Ch.11 - Liquids and Intermolecular Forces97
- Ch.12 - Solids and Modern Materials129
- Ch.13 - Properties of Solutions126
- Ch.14 - Chemical Kinetics175
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Acid-Base Equilibria127
- Ch.17 - Additional Aspects of Aqueous Equilibria133
- Ch.18 - Chemistry of the Environment88
- Ch.19 - Chemical Thermodynamics140
- Ch.20 - Electrochemistry137
- Ch.21 - Nuclear Chemistry99
- Ch.22 - Chemistry of the Nonmetals66
- Ch.23 - Transition Metals and Coordination Chemistry69
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry11
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 3, Problem 45b
Give the empirical formula of each of the following compounds if a sample contains (b) 2.10 g nickel and 0.58 g oxygen
Verified step by step guidance1
Step 1: The first step in determining the empirical formula of a compound is to convert the mass of each element to moles. This is done by dividing the given mass of each element by its atomic mass. The atomic mass of nickel (Ni) is approximately 58.69 g/mol and the atomic mass of oxygen (O) is approximately 16.00 g/mol.
Step 2: After converting the masses to moles, you will have the mole ratio of the elements in the compound. However, this ratio may not be in the simplest whole number form. To find the simplest whole number ratio, divide each value by the smallest number of moles calculated in the previous step.
Step 3: If the mole ratio obtained in the previous step is not a whole number, it may be necessary to multiply each value by a factor (such as 2, 3, etc.) to obtain whole numbers. This is often the case when dealing with elements that tend to form multiple bonds, like oxygen.
Step 4: Once you have the simplest whole number ratio of moles for each element, you can write the empirical formula. The empirical formula is written by listing the elements in the same order as in the original compound formula, followed by the number of atoms of each in subscript (if more than one).
Step 5: It's important to note that the empirical formula does not provide information about the actual number of atoms in a molecule of the compound, it only gives the simplest whole number ratio of atoms. The molecular formula may be a multiple of the empirical formula.
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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 is derived from the mass of each element in a sample and is crucial for understanding the composition of the substance. For example, if a compound contains elements A and B in a 1:2 ratio, its empirical formula would be AB2.
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Empirical vs Molecular Formula
Molar Mass
Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is essential for converting the mass of an element in a sample to the number of moles, which is necessary for determining the empirical formula. For instance, the molar mass of nickel (Ni) is approximately 58.69 g/mol, and for oxygen (O), it is about 16.00 g/mol.
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Stoichiometry
Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows chemists to calculate the amounts of substances involved based on their molar ratios. In the context of finding an empirical formula, stoichiometry helps in determining the mole ratio of the elements from their masses, which is fundamental for deriving the empirical formula.
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Related Practice
Textbook Question
At least 25 mg of tetrahydrocannabinol (THC), the active ingredient in marijuana, is required to produce intoxication. The molecular formula of THC is C21H30O2. How many molecules?
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Textbook Question
Determine the empirical formulas of the compounds with the following compositions by mass: (a) 74.0% C, 8.7% H, and 17.3% N
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Textbook Question
Give the empirical formula of each of the following compounds if a sample contains (c) 26.56% K, 35.41% Cr, and 38.03% O by mass.
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Textbook Question
The allowable concentration level of vinyl chloride, C2H3Cl, in the atmosphere in a chemical plant is 2.0⨉10−6 g/L. How many molecules per liter?
Textbook Question
At least 25 mg of tetrahydrocannabinol (THC), the active ingredient in marijuana, is required to produce intoxication. The molecular formula of THC is C21H30O2. How many moles of THC does this 25 mg represent?