Skip to main content
Chemistry LibreTexts

11: Reactions and Other Chemical Processes

  • Page ID
    20412
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    \( \newcommand{\tx}[1]{\text{#1}}      % text in math mode\)
     \( \newcommand{\subs}[1]{_{\text{#1}}} % subscript text\)
     \( \newcommand{\sups}[1]{^{\text{#1}}} % superscript text\)
     \( \newcommand{\st}{^\circ}            % standard state symbol\)
     \( \newcommand{\id}{^{\text{id}}}      % ideal\)
     \( \newcommand{\rf}{^{\text{ref}}}     % reference state\)
     \( \newcommand{\units}[1]{\mbox{$\thinspace$#1}}\)
     \( \newcommand{\K}{\units{K}}  % kelvins\)
     \( \newcommand{\degC}{^\circ\text{C}} % degrees Celsius\)
     \( \newcommand{\br}{\units{bar}}  % bar (\bar is already defined)\)
     \( \newcommand{\Pa}{\units{Pa}}\)
     \( \newcommand{\mol}{\units{mol}}  % mole\)
     \( \newcommand{\V}{\units{V}}  % volts\)
     \( \newcommand{\timesten}[1]{\mbox{$\,\times\,10^{#1}$}}\)
     \( \newcommand{\per}{^{-1}}  % minus one power\)
     \( \newcommand{\m}{_{\text{m}}}  % subscript m for molar quantity\)
     \( \newcommand{\CVm}{C_{V,\text{m}}} % molar heat capacity at const.V\)
     \( \newcommand{\Cpm}{C_{p,\text{m}}} % molar heat capacity at const.p\)
     \( \newcommand{\kT}{\kappa_T} % isothermal compressibility\)
     \( \newcommand{\A}{_{\text{A}}}  % subscript A for solvent or state A\)
     \( \newcommand{\B}{_{\text{B}}}  % subscript B for solute or state B\)
     \( \newcommand{\bd}{_{\text{b}}}  % subscript b for boundary or boiling point\)
     \( \newcommand{\C}{_{\text{C}}}  % subscript C\)
     \( \newcommand{\f}{_{\text{f}}}  % subscript f for freezing point\)
     \( \newcommand{\mA}{_{\text{m},\text{A}}} % subscript m,A (m=molar)\)
     \( \newcommand{\mB}{_{\text{m},\text{B}}} % subscript m,B (m=molar)\)
     \( \newcommand{\mi}{_{\text{m},i}}        % subscript m,i (m=molar)\)
     \( \newcommand{\fA}{_{\text{f},\text{A}}} % subscript f,A (for fr. pt.)\)
     \( \newcommand{\fB}{_{\text{f},\text{B}}} % subscript f,B (for fr. pt.)\)
     \( \newcommand{\xbB}{_{x,\text{B}}}       % x basis, B\)
     \( \newcommand{\xbC}{_{x,\text{C}}}       % x basis, C\)
     \( \newcommand{\cbB}{_{c,\text{B}}}       % c basis, B\)
     \( \newcommand{\mbB}{_{m,\text{B}}}       % m basis, B\)
     \( \newcommand{\kHi}{k_{\text{H},i}}      % Henry's law constant, x basis, i\)
     \( \newcommand{\kHB}{k_{\text{H,B}}}      % Henry's law constant, x basis, B\)
     \( \newcommand{\arrow}{\,\rightarrow\,} % right arrow with extra spaces\)
     \( \newcommand{\arrows}{\,\rightleftharpoons\,} % double arrows with extra spaces\)
     \( \newcommand{\ra}{\rightarrow} % right arrow (can be used in text mode)\)
     \( \newcommand{\eq}{\subs{eq}} % equilibrium state\)
     \( \newcommand{\onehalf}{\textstyle\frac{1}{2}\D} % small 1/2 for display equation\)
     \( \newcommand{\sys}{\subs{sys}} % system property\)
     \( \newcommand{\sur}{\sups{sur}} % surroundings\)
     \( \renewcommand{\in}{\sups{int}} % internal\)
     \( \newcommand{\lab}{\subs{lab}} % lab frame\)
     \( \newcommand{\cm}{\subs{cm}} % center of mass\)
     \( \newcommand{\rev}{\subs{rev}} % reversible\)
     \( \newcommand{\irr}{\subs{irr}} % irreversible\)
     \( \newcommand{\fric}{\subs{fric}} % friction\)
     \( \newcommand{\diss}{\subs{diss}} % dissipation\)
     \( \newcommand{\el}{\subs{el}} % electrical\)
     \( \newcommand{\cell}{\subs{cell}} % cell\)
     \( \newcommand{\As}{A\subs{s}} % surface area\)
     \( \newcommand{\E}{^\mathsf{E}} % excess quantity (superscript)\)
     \( \newcommand{\allni}{\{n_i \}} % set of all n_i\)
     \( \newcommand{\sol}{\hspace{-.1em}\tx{(sol)}}\)
     \( \newcommand{\solmB}{\tx{(sol,$\,$$m\B$)}}\)
     \( \newcommand{\dil}{\tx{(dil)}}\)
     \( \newcommand{\sln}{\tx{(sln)}}\)
     \( \newcommand{\mix}{\tx{(mix)}}\)
     \( \newcommand{\rxn}{\tx{(rxn)}}\)
     \( \newcommand{\expt}{\tx{(expt)}}\)
     \( \newcommand{\solid}{\tx{(s)}}\)
     \( \newcommand{\liquid}{\tx{(l)}}\)
     \( \newcommand{\gas}{\tx{(g)}}\)
     \( \newcommand{\pha}{\alpha}        % phase alpha\)
     \( \newcommand{\phb}{\beta}         % phase beta\)
     \( \newcommand{\phg}{\gamma}        % phase gamma\)
     \( \newcommand{\aph}{^{\alpha}}     % alpha phase superscript\)
     \( \newcommand{\bph}{^{\beta}}      % beta phase superscript\)
     \( \newcommand{\gph}{^{\gamma}}     % gamma phase superscript\)
     \( \newcommand{\aphp}{^{\alpha'}}   % alpha prime phase superscript\)
     \( \newcommand{\bphp}{^{\beta'}}    % beta prime phase superscript\)
     \( \newcommand{\gphp}{^{\gamma'}}   % gamma prime phase superscript\)
     \( \newcommand{\apht}{\small\aph} % alpha phase tiny superscript\)
     \( \newcommand{\bpht}{\small\bph} % beta phase tiny superscript\)
     \( \newcommand{\gpht}{\small\gph} % gamma phase tiny superscript\)

    \( \newcommand{\upOmega}{\Omega}\)

     \( \newcommand{\dif}{\mathop{}\!\mathrm{d}}   % roman d in math mode, preceded by space\)
     \( \newcommand{\Dif}{\mathop{}\!\mathrm{D}}   % roman D in math mode, preceded by space\)
     \( \newcommand{\df}{\dif\hspace{0.05em} f} % df\)

     \(\newcommand{\dBar}{\mathop{}\!\mathrm{d}\hspace-.3em\raise1.05ex{\Rule{.8ex}{.125ex}{0ex}}} % inexact differential \)
     \( \newcommand{\dq}{\dBar q} % heat differential\)
     \( \newcommand{\dw}{\dBar w} % work differential\)
     \( \newcommand{\dQ}{\dBar Q} % infinitesimal charge\)
     \( \newcommand{\dx}{\dif\hspace{0.05em} x} % dx\)
     \( \newcommand{\dt}{\dif\hspace{0.05em} t} % dt\)
     \( \newcommand{\difp}{\dif\hspace{0.05em} p} % dp\)
     \( \newcommand{\Del}{\Delta}\)
     \( \newcommand{\Delsub}[1]{\Delta_{\text{#1}}}\)
     \( \newcommand{\pd}[3]{(\partial #1 / \partial #2 )_{#3}} % \pd{}{}{} - partial derivative, one line\)
     \( \newcommand{\Pd}[3]{\left( \dfrac {\partial #1} {\partial #2}\right)_{#3}} % Pd{}{}{} - Partial derivative, built-up\)
     \( \newcommand{\bpd}[3]{[ \partial #1 / \partial #2 ]_{#3}}\)
     \( \newcommand{\bPd}[3]{\left[ \dfrac {\partial #1} {\partial #2}\right]_{#3}}\)
     \( \newcommand{\dotprod}{\small\bullet}\)
     \( \newcommand{\fug}{f} % fugacity\)
     \( \newcommand{\g}{\gamma} % solute activity coefficient, or gamma in general\)
     \( \newcommand{\G}{\varGamma} % activity coefficient of a reference state (pressure factor)\)
     \( \newcommand{\ecp}{\widetilde{\mu}} % electrochemical or total potential\)
     \( \newcommand{\Eeq}{E\subs{cell, eq}} % equilibrium cell potential\)
     \( \newcommand{\Ej}{E\subs{j}} % liquid junction potential\)
     \( \newcommand{\mue}{\mu\subs{e}} % electron chemical potential\)
    \( \newcommand{\defn}{\,\stackrel{\mathrm{def}}{=}\,} % "equal by definition" symbol\)

     \( \newcommand{\D}{\displaystyle} % for a line in built-up\)
     \( \newcommand{\s}{\smash[b]} % use in equations with conditions of validity\)
     \( \newcommand{\cond}[1]{\\[-2.5pt]{}\tag*{#1}}\)
     \( \newcommand{\nextcond}[1]{\\[-5pt]{}\tag*{#1}}\)
     \( \newcommand{\R}{8.3145\units{J$\,$K$\per\,$mol$\per$}}     % gas constant value\)
     \( \newcommand{\Rsix}{8.31447\units{J$\,$K$\per\,$mol$\per$}} % gas constant value - 6 sig figs\)

    \( \newcommand{\jn}{\hspace3pt\lower.3ex{\Rule{.6pt}{2ex}{0ex}}\hspace3pt} \)
    \( \newcommand{\ljn}{\hspace3pt\lower.3ex{\Rule{.6pt}{.5ex}{0ex}}\hspace-.6pt\raise.45ex{\Rule{.6pt}{.5ex}{0ex}}\hspace-.6pt\raise1.2ex{\Rule{.6pt}{.5ex}{0ex}} \hspace3pt} \)
    \( \newcommand{\lljn}{\hspace3pt\lower.3ex{\Rule{.6pt}{.5ex}{0ex}}\hspace-.6pt\raise.45ex{\Rule{.6pt}{.5ex}{0ex}}\hspace-.6pt\raise1.2ex{\Rule{.6pt}{.5ex}{0ex}}\hspace1.4pt\lower.3ex{\Rule{.6pt}{.5ex}{0ex}}\hspace-.6pt\raise.45ex{\Rule{.6pt}{.5ex}{0ex}}\hspace-.6pt\raise1.2ex{\Rule{.6pt}{.5ex}{0ex}}\hspace3pt} \) 

    This chapter discusses the thermodynamics of mixing processes and processes described by reaction equations (chemical equations). It introduces the important concepts of molar mixing and reaction quantities, advancement, and the thermodynamic equilibrium constant. The focus is on chemical processes that take place in closed systems at constant pressure, with no work other than expansion work. Under these conditions, the enthalpy change is equal to the heat (Eq. 5.3.7). The processes either take place at constant temperature, or have initial and final states of the same temperature.

    Most of the processes to be described involve mixtures and have intermediate states that are nonequilibrium states. At constant temperature and pressure, these processes proceed spontaneously with decreasing Gibbs energy (Sec. 5.8). (Processes in which \(G\) decreases are sometimes called exergonic.) When the rates of change are slow enough for thermal and mechanical equilibrium to be maintained, the spontaneity is due to lack of transfer equilibrium or reaction equilibrium. An equilibrium phase transition of a pure substance, however, is a special case: it is a reversible process of constant Gibbs energy (Sec. 8.3).

    Contributors


    This page titled 11: Reactions and Other Chemical Processes is shared under a CC BY 4.0 license and was authored, remixed, and/or curated by Howard DeVoe via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request.

    • Was this article helpful?