5: Chemical Reactions- Making Materials Safely and Sustainable
- Page ID
- 285296
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)“The materials that we make and the ways that we make them have an enormous impact on Earth’s environment. Much of green chemistry has to do with making materials safely and sustainably.”
- 5.1: Describing What Happens with Chemical Equations
- This page outlines the human body as a complex chemical factory, highlighting metabolic reactions like glucose transformation. It stresses the significance of chemical equations that represent reactants and products while following the conservation of mass. Key topics include balancing equations, identifying physical states, understanding reversible reactions, and using symbols such as ∆ for heat.
- 5.2: Balancing Chemical Equations
- This page details the process of balancing chemical equations, highlighting the necessity for equal atom counts on both sides. It provides an illustration of methane's reaction with chlorine to yield dichloromethane and hydrogen chloride, and tackles a complex reaction involving iron oxide. The text emphasizes not changing chemical formulas and includes exercises with solutions for practice.
- 5.3: Just Because You Can Write It Doesn't Mean That It Will Happen
- This page explains that a balanced chemical equation does not ensure a reaction will happen, as seen with copper and sulfuric acid. It details an alternative pathway to produce copper sulfate and highlights green chemistry's focus on safer reaction methods with fewer byproducts. Specifically, it compares two methods for making iron sulfate, noting that one releases hazardous hydrogen gas while the other yields only water, emphasizing the importance of safety in chemical reactions.
- 5.4: Yield And Atom Economy in Chemical Reactions
- This page covers yield and atom economy in green chemistry, using HCl gas preparation as an example. Yield measures the completeness of a reaction, while atom economy indicates the efficiency of reactants converted to desired products. A reaction of sulfuric acid with sodium chloride shows 100% yield but only 34% atom economy due to Na2SO4 byproduct. Conversely, the direct reaction of hydrogen with chlorine achieves both 100% yield and atom economy, with no waste generated.
- 5.5: Catalysts That Make Reactions Go
- This page discusses the conversion of carbon monoxide (CO) to carbon dioxide (CO2) using catalysts in automotive catalytic converters. It highlights the role of catalysts in speeding up chemical reactions without being consumed, similar to enzymes that facilitate biological processes, including respiration.
- 5.6: Kinds of Chemical Reactions
- This page categorizes chemical reactions into combination, decomposition, substitution, and metathesis. Combination reactions produce a single product with full atom economy, while decomposition reactions break down substances. Substitution replaces elements within compounds, and double replacement exchanges ions, often causing precipitation. It highlights the significance of these classifications in the context of green chemistry practices.
- 5.7: Oxidation-Reduction Reactions and Green Chemistry
- This page discusses oxidation-reduction (redox) reactions, highlighting the processes of electron transfer, where oxidation is the loss of electrons and reduction is the gain. It illustrates redox reactions with examples like calcium and oxygen, and notes their relevance in electrolysis, photosynthesis, and fossil fuel combustion.
- 5.8: Quantitative Information from Chemical Reactions
- This page discusses green chemistry, emphasizing the importance of calculating material quantities in chemical reactions, specifically percent yield and atom economy. It highlights the need for balanced chemical reactions and atomic formula masses for accurate calculations. While individual atoms are measured in atomic mass units, laboratory work utilizes grams and moles, with a mole generally weighing several grams.
- 5.9: Energy in Chemical Reactions
- This page explores the significance of energy in chemical reactions, particularly heat and chemical energy in bonds. It uses the example of methane combustion to illustrate the release of 802 kJ of energy, characterizing the reaction as exothermic. The text emphasizes the correlation between heat energy released and bond energy differences, and discusses the effective capture of heat in condensing gas furnaces.
- 5.10: Stoichiometry by the Mole Ratio Method
- This page covers stoichiometry and the calculation of material quantities in chemical reactions, particularly the combustion of ethane (C2H6) with oxygen. It emphasizes mass conservation, detailing how to compute the reactants and products' masses using molar ratios. Examples include ethane and aluminum reactions.
- 5.11: Limiting Reactant and Percent Yield
- This page discusses the concept of limiting reactants in chemical reactions, providing examples such as the reaction between zinc and sulfur, where zinc limits product formation, and hydrochloric acid with aluminum, highlighting HCl as the limiting reactant. It also explains percent yield through a reaction between CaCl2 and Na2SO4, calculating a percent yield of 92.5% from an actual yield of 28.3 g compared to the stoichiometric yield of 30.6 g.
- 5.12: Titrations - Measuring Moles by Volume of Solution
- This page discusses mass measurement using balances and scales, emphasizes the role of titration in laboratory stoichiometry, and provides examples involving hydrochloric acid and calcium hydroxide. It details the chemical calculation for converting moles of HCl to moles and mass of Ca(OH)₂, resulting in a percentage of 13.9%. Additionally, it covers titration exercises with oxalic acid and sodium hydroxide, revealing that the oxalic acid percentage in the sample is 38.9%.
- 5.13: Industrial Chemical Reactions - The Solvay Process
- This page discusses the Solvay process for producing sodium bicarbonate and sodium carbonate, essential for industries like glassmaking. It details the key reactions and emphasizes material recycling for cost efficiency. However, it highlights environmental concerns such as greenhouse gas emissions and the impact of raw material extraction. Additionally, it notes that natural trona deposits have led to a reduced reliance on the Solvay process in the U.S.
- Questions and Problems
- This page covers the classification, balancing, and interpretation of chemical equations and reactions, focusing on stoichiometry, reactant states, and metal reactions with acids. It highlights practical applications like titrations and the Solvay process, while addressing theoretical concepts such as limiting reactants and stoichiometric yields.