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Ch.3 - Chemical Reactions and Reaction Stoichiometry
Brown - Chemistry: The Central Science 14th Edition
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
All textbooksBrown 14th EditionCh.3 - Chemical Reactions and Reaction StoichiometryProblem 102
Chapter 3, Problem 102

When hydrocarbons are burned in a limited amount of air, both CO and CO2 form. When 0.450 g of a particular hydrocarbon was burned in air, 0.467 g of CO, 0.733 g of CO2, and 0.450 g of H2O were formed. (a) What is the empirical formula of the compound? (b) How many grams of O2 were used in the reaction? (c) How many grams would have been required for complete combustion?

Verified step by step guidance
1
Step 1: Determine the moles of CO and CO2 produced. Use the molar masses of CO (28.01 g/mol) and CO2 (44.01 g/mol) to convert the given masses to moles.
Step 2: Calculate the total moles of carbon atoms in the products. Since each mole of CO and CO2 contains one mole of carbon, add the moles of carbon from CO and CO2.
Step 3: Determine the moles of H2O produced. Use the molar mass of H2O (18.02 g/mol) to convert the given mass to moles. Each mole of H2O contains two moles of hydrogen atoms.
Step 4: Calculate the empirical formula. Use the moles of carbon and hydrogen obtained from the products to find the simplest whole number ratio of carbon to hydrogen in the hydrocarbon.
Step 5: Calculate the moles of oxygen used. Use the stoichiometry of the reaction to determine the moles of O2 consumed, considering the moles of CO, CO2, and H2O produced.

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. To determine the empirical formula, one must first convert the masses of the products formed during combustion into moles, then find the ratio of moles of each element. This concept is crucial for identifying the basic composition of the hydrocarbon in question.
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Empirical vs Molecular Formula

Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between the reactants and products in a chemical reaction. It allows us to calculate the amounts of substances consumed and produced in a reaction based on balanced chemical equations. Understanding stoichiometry is essential for determining how much O2 was used and how much would be needed for complete combustion.
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Stoichiometry Concept

Combustion Reaction

A combustion reaction is a chemical process in which a hydrocarbon reacts with oxygen to produce carbon dioxide and water, typically releasing energy. Incomplete combustion occurs when there is insufficient oxygen, leading to the formation of carbon monoxide alongside carbon dioxide. Recognizing the differences between complete and incomplete combustion is vital for solving the problem regarding the amounts of O2 required.
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Related Practice
Textbook Question

A method used by the U.S. Environmental Protection Agency (EPA) for determining the concentration of ozone in air is to pass the air sample through a 'bubbler' containing sodium iodide, which removes the ozone according to the following equation: O31g2 + 2 NaI1aq2 + H2O1l2¡ O21g2 + I21s2 + 2 NaOH1aq2 (b) How many grams of sodium iodide are needed to remove 1.3 mg of O3?

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Textbook Question

A mixture of N21g2 and H21g2 reacts in a closed container to form ammonia, NH31g2. The reaction ceases before either reactant has been totally consumed. At this stage 3.0 mol N2, 3.0 mol H2, and 3.0 mol NH3 are present. How many moles of N2 and H2 were present originally?

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Textbook Question

When a mixture of 10.0 g of acetylene (C2H2) and 10.0 g of oxygen (O2) is ignited, the resulting combustion reaction produces CO2 and H2O. (c) How many grams of C2H2 are present after the reaction is complete?

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Textbook Question

The fat stored in a camel's hump is a source of both energy and water. Calculate the mass of H2O produced by the metabolism of 1.0 kg of fat, assuming the fat consists entirely of tristearin 1C57H110O62, a typical animal fat, and assuming that during metabolism, tristearin reacts with O2 to form only CO2 and H2O.

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Textbook Question

An element X forms an iodide (XI3) and a chloride (XCl3). The iodide is quantitatively converted to the chloride when it is heated in a stream of chlorine: 2 XI3 + 3 Cl2 → 2 XCl3 + 3 I2 If 0.5000 g of XI3 is treated with chlorine, 0.2360 g of XCl3 is obtained. (a) Calculate the atomic weight of the element X. (b) Identify the element X.

992
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Textbook Question

When a mixture of 10.0 g of acetylene (C2H2) and 10.0 g of oxygen (O2) is ignited, the resulting combustion reaction produces CO2 and H2O. (c) How many grams of CO2 and H2O are present after the reaction is complete?

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