Chemistry
Stoichiometry in Reactions
Stoichiometry in reactions refers to the quantitative relationship between the amounts of reactants and products in a chemical reaction. It involves using balanced chemical equations to determine the mole ratios of substances involved in the reaction. This allows for the calculation of the amount of products formed from a given amount of reactants, and vice versa.
Written by Perlego with AI-assistance
Related key terms
1 of 5
10 Key excerpts on "Stoichiometry in Reactions"
eBook - PDFElementary Chemical Reactor Analysis
Butterworths Series in Chemical Engineering
- Rutherford Aris(Author)
- 2013(Publication Date)
- Butterworth-Heinemann(Publisher)
Stoichiometry 2.1 What It Is and Why We Need It The strict meaning of the word stoichiometry is measurement of the ele-ments, but it is commonly used to refer to all manner of calculations regarding the composition of a chemical system. We shall give it a broad meaning here for we are concerned as much with the algebra of the relationship between the chemical species as with the arithmetical calculations that are implied. Stoichiometry is essentially the bookkeeping of the material components of the chemical system. Its importance lies in the fact that the changes in composition in a reactor are not haphazard, but are of two distinct kinds. First, there are the advective changes due to material brought into the system or removed from it; this may be by forced flow, convection, or diffusion. Second, there is the internal change of composition by reaction; this change would be seen in a well-stirred batch reactor, for example, where advection has been deliberately eliminated. The advection will have to be expressed by certain terms in the material balance for a particular reactor, but the reactive changes are com-mon to all types and deserve study first. To see the nature of the restrictions on possible changes in composition let us recall a universally known reaction 2H 2 + 0 2 = 2H 2 0. (2.1.1) An equation such as this can have two meanings. It may be a kinetic description of the reaction and imply that two molecules of hydrogen com-8 2 Sec. 2.2 Entire Reactions and Reaction Mechanisms 9 bine directly with one of oxygen to form two molecules of water. In this particular case, Eq. (2.1.1) is not true as a kinetic description. On the other hand, it may be a stoichiometric description of the reaction, and the equa-tion will then mean that the numbers of hydrogen and oxygen molecules combining to form water are in the ratio 2 : 1.
eBook - PDF- Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2019(Publication Date)
- Openstax(Publisher)
These quantitative relationships are known as the reaction’s stoichiometry, a term derived from the Greek words stoicheion (meaning “element”) and metron (meaning “measure”). In this module, the use of balanced chemical equations for various stoichiometric applications is explored. The general approach to using stoichiometric relationships is similar in concept to the way people go about many common activities. Food preparation, for example, offers an appropriate comparison. A recipe for making eight pancakes calls for 1 cup pancake mix, cup milk, and one egg. The “equation” representing the preparation of pancakes per this recipe is If two dozen pancakes are needed for a big family breakfast, the ingredient amounts must be increased proportionally according to the amounts given in the recipe. For example, the number of eggs required to make 24 pancakes is Balanced chemical equations are used in much the same fashion to determine the amount of one reactant required to react with a given amount of another reactant, or to yield a given amount of product, and so forth. The coefficients in the balanced equation are used to derive stoichiometric factors that permit computation of the desired quantity. To illustrate this idea, consider the production of ammonia by reaction of hydrogen and nitrogen: This equation shows ammonia molecules are produced from hydrogen molecules in a 2:3 ratio, and stoichiometric factors may be derived using any amount (number) unit: These stoichiometric factors can be used to compute the number of ammonia molecules produced from a given number of hydrogen molecules, or the number of hydrogen molecules required to produce a given number of ammonia molecules. Similar factors may be derived for any pair of substances in any chemical equation.
- Morris Hein, Scott Pattison, Susan Arena, Leo R. Best(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
12.1 • Properties of Gases 167 Corbis RF/Age Fotostock America, Inc. T he old adage “waste not, want not” is appropriate in our daily life and in the laboratory. Determining correct amounts comes into play in almost all professions. A seamstress determines the amount of material, lining, and trim necessary to produce a gown for her client by relying on a pattern or her own experience to guide the selection. A carpet layer de- termines the correct amount of carpet and padding necessary to recarpet a customer’s house by calculating the floor area. The IRS determines the correct deduction for federal income taxes from your paycheck based on your expected annual income. 9.1 Introduction to Stoichiometry 9.2 Mole–Mole Calculations 9.3 Mole–Mass Calculations 9.4 Mass–Mass Calculations 9.5 Limiting Reactant and Yield Calculations CALCULATIONS FROM CHEMICAL EQUATIONS C H A P T E R 9 Accurate calculations of dose and accurate measurement of chemicals are required in order for a pharmacist to dispense the correct dosage of medicine to her patients. C H A P T E R O U T L I N E 168 CHAPTER 9 • Calculations from Chemical Equations 9.1 INTRODUCTION TO STOICHIOMETRY Define stoichiometry and describe the strategy required to solve problems based on chemical equations. We often need to calculate the amount of a substance that is either produced from, or needed to react with, a given quantity of another substance. The area of chemistry that deals with quantitative relationships among reactants and products is known as stoichiometry (stoy-key-ah-meh-tree). Solving problems in stoichiometry requires the use of moles in the form of mole ratios. The chemist also finds it necessary to calculate amounts of products or reactants by using a balanced chemical equation. With these calculations, the chemist can control the amount of product by scaling the reaction up or down to fit the needs of the laboratory and can thereby minimize waste or excess materials formed during the reaction.
eBook - PDF- Allan Blackman, Steven E. Bottle, Siegbert Schmid, Mauro Mocerino, Uta Wille(Authors)
- 2022(Publication Date)
- Wiley(Publisher)
A reactant present in a smaller amount is called a limiting reagent. The theoretical yield of a product can be no more than that permitted by the limiting reagent. Sometimes, competing reactions (side reactions) that produce by-products reduce the actual yield. The ratio of the actual yield to the theoretical yield, expressed as a percentage, is the percentage yield. 3.6 Apply stoichiometric concepts to reactions in solutions. A solution is a homogeneous mixture in which one or more solutes are dissolved in a solvent. Concentration is the ratio of the amount of solute to the volume of solution. Solutions of known concentration can be prepared by weighing accurate masses of compounds using an analytical balance and then making them up to a particular volume with solvent in a vol- umetric flask. Concentrated solutions of known concentration can be diluted quantitatively using volumetric glassware such as pipettes and volumetric flasks. Molarity is a useful concentration unit for any calculation involving the stoichiometry of reactions in solution. In ionic reactions, the concentrations of the ions in a solution of a salt can be derived from the molar concentration of the salt, taking into account the number of ions formed on dissolution of the salt. For reactions involving ions there are three possible ways to write reaction equations. A molecular equation uses the empirical formula for each compound to aid stoichiometric calculations. The ionic equation shows all the ions that are formed in solution, while the net ionic equation shows only those ions that are actually involved in the net reaction (i.e. excluding spectator ions). CHAPTER 3 Chemical reactions and stoichiometry 125 KEY CONCEPTS AND EQUATIONS Concept Section Description/equation Chemical formula 3.1 We use subscripts in a formula to establish atom ratios and mole ratios between the elements in the substance.
eBook - PDF- Morris Hein, Susan Arena, Cary Willard(Authors)
- 2016(Publication Date)
- Wiley(Publisher)
T he old adage “waste not, want not” is appropriate in our daily life and in the laboratory. Determining cor- rect amounts comes into play in almost all professions. A seamstress determines the amount of material, lining, and trim necessary to produce a gown for her client by rely- ing on a pattern or her own experience to guide the selec- tion. A carpet layer determines the correct amount of carpet and padding necessary to recarpet a customer’s house by calculating the floor area. The IRS determines the correct deduction for federal income taxes from your paycheck based on your expected annual income. In chemistry, calculations from chemical equations are important too. These same calculations and amounts are used frequently in medicine and pharmacy. Accurate calculations of dose and accurate measurement of chemicals are required in order for a pharmacist to dispense the correct dosage of medicine to her patients. Calculations from Chemical Equations Corbis RF/Age Fotostock America, Inc. 9 C H A P T E R O U T L I N E 9.1 Introduction to Stoichiometry 9.2 Mole–Mole Calculations 9.3 Mole–Mass Calculations 9.4 Mass–Mass Calculations 9.5 Limiting Reactant and Yield Calculations 176 CHAPTER 9 Calculations from Chemical Equationss 9.1 Introduction to Stoichiometry Define stoichiometry and describe the strategy required to solve problems based on chemical equations. We often need to calculate the amount of a substance that is either produced from, or need- ed to react with, a given quantity of another substance. The area of chemistry that deals with quantitative relationships among reactants and products is known as stoichiometry (stoy-key-ah-meh-tree). Solving problems in stoichiometry requires the use of moles in the form of mole ratios. The chemist also finds it necessary to calculate amounts of products or reactants by using a balanced chemical equation.
eBook - PDF- William R. Robinson, Edward J. Neth, Paul Flowers, Klaus Theopold, Richard Langley(Authors)
- 2016(Publication Date)
- Openstax(Publisher)
In this module, the use of balanced chemical equations for various stoichiometric applications is explored. The general approach to using stoichiometric relationships is similar in concept to the way people go about many common activities. Food preparation, for example, offers an appropriate comparison. A recipe for making eight pancakes calls for 1 cup pancake mix, 3 4 cup milk, and one egg. The “equation” representing the preparation of pancakes per this recipe is 1 cup mix + 3 4 cup milk + 1 egg ⟶ 8 pancakes If two dozen pancakes are needed for a big family breakfast, the ingredient amounts must be increased proportionally according to the amounts given in the recipe. For example, the number of eggs required to make 24 pancakes is 24 pancakes × 1 egg 8 pancakes = 3 eggs Balanced chemical equations are used in much the same fashion to determine the amount of one reactant required to react with a given amount of another reactant, or to yield a given amount of product, and so forth. The coefficients in the balanced equation are used to derive stoichiometric factors that permit computation of the desired quantity. To Chapter 7 | Stoichiometry of Chemical Reactions 361 illustrate this idea, consider the production of ammonia by reaction of hydrogen and nitrogen: N 2 (g) + 3H 2 (g) ⟶ 2NH 3 (g) This equation shows ammonia molecules are produced from hydrogen molecules in a 2:3 ratio, and stoichiometric factors may be derived using any amount (number) unit: 2 NH 3 molecules 3 H 2 molecules or 2 doz NH 3 molecules 3 doz H 2 molecules or 2 mol NH 3 molecules 3 mol H 2 molecules These stoichiometric factors can be used to compute the number of ammonia molecules produced from a given number of hydrogen molecules, or the number of hydrogen molecules required to produce a given number of ammonia molecules. Similar factors may be derived for any pair of substances in any chemical equation.
eBook - PDF- Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2015(Publication Date)
- Openstax(Publisher)
In this module, the use of balanced chemical equations for various stoichiometric applications is explored. The general approach to using stoichiometric relationships is similar in concept to the way people go about many common activities. Food preparation, for example, offers an appropriate comparison. A recipe for making eight pancakes calls for 1 cup pancake mix, 3 4 cup milk, and one egg. The “equation” representing the preparation of pancakes per this recipe is 1 cup mix + 3 4 cup milk + 1 egg ⟶ 8 pancakes If two dozen pancakes are needed for a big family breakfast, the ingredient amounts must be increased proportionally according to the amounts given in the recipe. For example, the number of eggs required to make 24 pancakes is 24 pancakes × 1 egg 8 pancakes = 3 eggs Balanced chemical equations are used in much the same fashion to determine the amount of one reactant required to react with a given amount of another reactant, or to yield a given amount of product, and so forth. The coefficients in the balanced equation are used to derive stoichiometric factors that permit computation of the desired quantity. To Chapter 4 | Stoichiometry of Chemical Reactions 193 illustrate this idea, consider the production of ammonia by reaction of hydrogen and nitrogen: N 2 (g) + 3H 2 (g) ⟶ 2NH 3 (g) This equation shows ammonia molecules are produced from hydrogen molecules in a 2:3 ratio, and stoichiometric factors may be derived using any amount (number) unit: 2 NH 3 molecules 3 H 2 molecules or 2 doz NH 3 molecules 3 doz H 2 molecules or 2 mol NH 3 molecules 3 mol H 2 molecules These stoichiometric factors can be used to compute the number of ammonia molecules produced from a given number of hydrogen molecules, or the number of hydrogen molecules required to produce a given number of ammonia molecules. Similar factors may be derived for any pair of substances in any chemical equation.
eBook - PDF- Edward J. Neth, Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson(Authors)
- 2019(Publication Date)
- Openstax(Publisher)
INTRODUCTION CHAPTER 7 Stoichiometry of Chemical Reactions 7.1 Writing and Balancing Chemical Equations 7.2 Classifying Chemical Reactions 7.3 Reaction Stoichiometry 7.4 Reaction Yields 7.5 Quantitative Chemical Analysis Solid-fuel rockets are a central feature in the world’s space exploration programs, including the new Space Launch System being developed by the National Aeronautics and Space Administration (NASA) to replace the retired Space Shuttle fleet ( Figure 7.1). The engines of these rockets rely on carefully prepared solid mixtures of chemicals combined in precisely measured amounts. Igniting the mixture initiates a vigorous chemical reaction that rapidly generates large amounts of gaseous products. These gases are ejected from the rocket engine through its nozzle, providing the thrust needed to propel heavy payloads into space. Both the nature of this chemical reaction and the relationships between the amounts of the substances being consumed and produced by the reaction are critically important considerations that determine the success of the technology. This chapter will describe how to symbolize chemical reactions using chemical equations, how to classify some common chemical reactions by identifying patterns of reactivity, and how to determine the quantitative relations between the amounts of substances involved in chemical reactions—that is, the reaction stoichiometry. Figure 7.1 Many modern rocket fuels are solid mixtures of substances combined in carefully measured amounts and ignited to yield a thrust-generating chemical reaction. (credit: modification of work by NASA) CHAPTER OUTLINE 7.1 Writing and Balancing Chemical Equations LEARNING OBJECTIVES By the end of this section, you will be able to: • Derive chemical equations from narrative descriptions of chemical reactions. • Write and balance chemical equations in molecular, total ionic, and net ionic formats.
eBook - PDFChemistry
An Atoms First Approach
- Steven Zumdahl, Susan Zumdahl, Donald J. DeCoste, , Steven Zumdahl, Steven Zumdahl, Susan Zumdahl, Donald J. DeCoste(Authors)
- 2020(Publication Date)
- Cengage Learning EMEA(Publisher)
ions 230 CHAPTER 5 Stoichiometry Copyright 2021 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Stoichiometry Calculations ❯ Amounts of reactants consumed and products formed can be determined from the balanced chemical equation ❯ The limiting reactant is the one consumed first, thus limiting the amount of product that can form Yield ❯ The theoretical yield is the maximum amount that can be produced from a given amount of the limiting reactant ❯ The actual yield, the amount of product actually obtained, is always less than the theoretical yield ❯ Percent yield 5 actual yield sgd theoretical yield sgd 3 100% 1. Explain the concept of “counting by weighing” using marbles as your example. 2. Atomic masses are relative masses. What does this mean? 3. The atomic mass of boron (B) is given in the periodic table as 10.81, yet no single atom of boron has a mass of 10.81 u. Explain. 4. What are three conversion factors and in what order would you use them to convert the mass of a compound into atoms of a particular element in that compound— for example, from 1.00 g aspirin (C 9 H 8 O 4 ) to number of hydrogen atoms in the 1.00-g sample? 5. Fig. 5.5 illustrates a schematic diagram of a combustion device used to analyze organic compounds. Given that a certain amount of a compound containing carbon, hydrogen, and oxygen is combusted in this device, explain how the data relating to the mass of CO 2 pro- duced and the mass of H 2 O produced can be manipu- lated to determine the empirical formula.
eBook - PDFChemistry
The Molecular Nature of Matter
- James E. Brady, Neil D. Jespersen, Alison Hyslop(Authors)
- 2014(Publication Date)
- Wiley(Publisher)
Empirical formulas from percentage composition (Section 3.4) Percentage composition correlates information from different experiments, to determine empirical formulas. Balancing chemical equations (Section 3.5) Balancing equations involves writing the unbalanced equation and then adjusting the coefficients to get equal numbers of each kind of atom on both sides of the arrow. Equivalencies obtained from balanced equations (Section 3.5) The coefficients in balanced chemical equations give us relationships between all reactants and products that can be used in factor- label calculations. Mass-to-mass calculations using balanced chemical equations (Section 3.5) A logical sequence of conversions allows calculation of all components of a chemical reaction. See Figure 3.6. Tools for Problem Solving The following tools were introduced in this chapter. Study them carefully so you can select the appropriate tool when needed. 146 Chapter 3 | The Mole and Stoichiometry Limiting reactant calculations (Section 3.6) When the amounts of at least two reactants are given, one will be used up before the other and dictate the amont of products formed and the amount of excess reactant left over. Theoretical, actual, and percentage yields (Section 3.7) The theoretical yield is based on the limiting reactant whether stated, implied, or calculated. The actual yield must be determined by experiment, and the percentage yield relates the magnitude of the actual yield to the percentage yield. Percentage yield = actual mass by experiment theoretical mass by calculation Ž 100% Multi-step percentage yield (Section 3.7) Modern chemical synthesis often involves more than one distinct reaction or step. The overall percentage yield of a multi-step synthesis is Overall % yield = a % yield 1 100 Ž % yield 2 100 Ž ... b 100% Review Questions 147 =WileyPLUS, an online teaching and learning solution.
Index pages curate the most relevant extracts from our library of academic textbooks. They’ve been created using an in-house natural language model (NLM), each adding context and meaning to key research topics.
