8: Quantities in Chemical Reactions
- Page ID
- 47422
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)So far, we have talked about chemical reactions in terms of individual atoms and molecules. Although this works, most of the reactions occurring around us involve much larger amounts of chemicals. Even a tiny sample of a substance will contain millions, billions, or a hundred billion billions of atoms and molecules. How do we compare amounts of substances to each other, in chemical terms, when it is so difficult to count to a hundred billion billion? Actually, there are ways to do this, which we will explore in this chapter. In doing so, we will increase our understanding of stoichiometry, which is the study of the numerical relationships between the reactants and the products in a balanced chemical reaction.
- 8.1: Climate Change - Too Much Carbon Dioxide
- This page discusses the significance of carbon dioxide (CO2) as a greenhouse gas, emphasizing its rise due to human activities, particularly fossil fuel combustion. Since the Industrial Revolution, CO2 levels have increased substantially, with human actions accounting for around 82.2% of U.S. greenhouse gas emissions in 2015. This rise disrupts the natural carbon cycle and impacts carbon sinks like forests, illustrating the critical role of energy and transportation in CO2 emissions.
- 8.3: Making Molecules- Mole-to-Mole Conversions
- This page covers the interpretation of balanced chemical equations focusing on molar relationships and the significance of coefficients. It discusses stoichiometry, using examples to illustrate how to apply mole ratios from equations for calculating reactant amounts and product yields. Exercises are included to enable readers to practice these principles for future calculations.
- 8.4: Making Molecules- Mass-to-Mass Conversions
- This page covers mole-mass conversions in stoichiometry, highlighting the use of balanced chemical equations for calculating mass or moles of substances. It presents a systematic approach using molar ratios and molar masses, illustrated with examples such as the mass of \(\ce{SO3}\) for reactions and mass-mass calculations.
- 8.5: Stoichiometry
- This page introduces stoichiometry, focusing on the calculation of reactant and product quantities in chemical reactions via balanced equations. It explains the role of coefficients in representing relative amounts and uses examples like the Haber process for ammonia production. The mole is emphasized as a crucial unit for quantifying particles, relating to the conservation of mass.
- 8.6: Limiting Reactant and Theoretical Yield
- This page covers limiting reactants in chemical reactions, highlighting their role in restricting product formation. It presents two methods for identification: stoichiometric mole ratio comparisons and mass yield calculations. Several relatable examples, including baking and chemical reactions, illustrate these approaches.
- 8.7: Limiting Reactant, Theoretical Yield, and Percent Yield from Initial Masses of Reactants
- This page explains the concept of percent yield in chemical reactions, particularly in pharmaceuticals, where it assesses efficiency and cost through a comparison of actual and theoretical yields. It emphasizes the significance of determining percent yield, factors affecting it (such as incomplete reactions), and the role of purification in obtaining accurate measurements.
- 8.8: Enthalpy Change is a Measure of the Heat Evolved or Absorbed
- This page covers energy transfer in physical and chemical changes, focusing on the law of conservation of energy. It explains system vs. surroundings, endothermic and exothermic reactions, and enthalpy changes (ΔH) at constant pressure. Thermochemical equations link enthalpy changes to chemical transformations. It includes a calculation of ΔH for the reaction between sulfur dioxide and oxygen to form sulfur trioxide, demonstrating an exothermic reaction with a heat release of 89.6 kJ for 58.