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\fancyhead[LO,LE]{Unit 3 Chemistry Revision Lecture}
\fancyhead[CO,CE]{Andrew Lorimer}

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  \title{\large Year 12 Chemistry \\ \huge Unit 3 Revision Lecture \\ \large Monash University \\ presented by Peter Skinner}
  \author{Andrew Lorimer}
  \date{4 July 2019}
  \renewcommand{\abstractname}{}
  \maketitle

  \section{Course structure}
  \begin{itemize}
    \item \textbf{Unit 3:} 2 SACs, 16\% of study score
      \begin{enumerate}
        \item Energy production
          \begin{itemize}
            \item Obtaining energy from fuels
            \item Fuel choices
            \item Galvanic cells
            \item Fuel cells
          \end{itemize}
        \item Optimising yield
          \begin{itemize}
            \item Rate of reactions
            \item Extent of reactions
            \item Production via electrolysis
            \item Rechargable batteries
          \end{itemize}
      \end{enumerate}
    \item \textbf{Unit 4:} 3 SACs, 24\% of study score
    \item \textbf{Exam:} 60\% of study score
      \begin{itemize}
        \item 15 minutes reading time, 2.5 hours writing time
        \item 30 multiple choice questions (spend 30---45 minutes, \textbf{do last}) - harder in new study design
        \item 90 marks written questions (spend 1 hr 45 m---2 hr)\\
          Last year:
          \begin{itemize}
            \item 23\% calculations (21 marks)
            \item 44\% extended answer (40 marks)
            \item 32\% short answer (29 marks)
          \end{itemize}
        \item 5---10 marks on writing chemical equations
        \item Same marking panel as last year
        \item Indirect assessment of pracs
        \item $\ge$ 1 mark for significant figures
        \item Importance of written communication
        \item First parts are important, no consequential marks
        \item Use dot points (short form) - especially in rates \& concentration
      \end{itemize}
  \end{itemize}
  
  \begin{tcolorbox}[title=Key points]
  \begin{itemize}
    \item Spend 30---45 minutes on multiple choice
    \item Focus on redox reactions
    \item Use data book
    \item Multiple choice questions are hard
    \item Memorise oxidation numbers
  \end{itemize}
  \end{tcolorbox}

  \section{Energy production}
  
  \begin{itemize}
    \item $C=n \div v$ or $C=m \div V$ (concentration in g L$^{-1}$)
    \item Gases: $PV=nRT$ and \colorbox{important}{$n=V \div V_m$}
    \item Past exams before 2017 use different SLC
    \item Renewability - \textit{reasonable} timeframe
    \item Fuel choices - consider:
      \begin{itemize}
        \item External temperature
        \item Viscosity \colorbox{important}{(intermolecular forces)}
        \item Hygroscopic properties \colorbox{important}{(attracts water $\implies$ forms H-bonds)}
        \item \colorbox{important}{Cloud point}
      \end{itemize}
    \item Blended fuels - \colorbox{important}{use energy per mass not energy per mol}
  \end{itemize}


  \section{Yield \& rate}

  \begin{itemize}
    \item \colorbox{important}{Equilibrium constant $K_C$ needs units}
    \item $K_C \equiv K$
    \item Example question for rates: limiting factor for rate, given a set (equal) rate of both reactants consumption/production
    \item Collision theory:
      \begin{enumerate}
        \item Particles must collide
        \item Particles must collide with sufficient energy to overcome $E_A$
      \end{enumerate}
    \item Increase of rate with temperature:
      \begin{enumerate}
        \item $\uparrow$ temperature $\implies \uparrow$ energy $\implies$ more frequent collisions
        \item $\uparrow$ temperature $\implies \uparrow$ energy $\implies$ collisions occur with greater energy\\
          ($\implies$ greater \textit{proportion} of particles that can react per unit time)
      \end{enumerate}
    \item $\uparrow c(\text{reactants}) \implies $ more collisions 
    \item Definition of \textit{rate}: more products per unit time $\longrightarrow$ faster rate
    \item Cause and effect: propose hypothesis and prove by induction
    \item Maxwell-Boltzmann distributions - $x_{\text{peak}}$ is constant for different concentrations
    \item \colorbox{important}{Memorise definition of \textit{catalyst}:} provides a reaction with an alternative energy pathway which has a lower activation energy
  \end{itemize}

  \subsection{Equilibria}
  \begin{itemize}
    \item \colorbox{important}{all} reactants and products are present at equilibrium
    \item $K_C$ is fixed at a constant temperature and reaction
    \item $K_C$ changes with concentrations (relative)
    \item If reaction equation is reversed, $K_C$ value will be the reciprocal
    \item If temperature changes, $K_C$ will change (but \colorbox{important}{not necessarily proportionally})
    \item Le Chatelier's principle:\\
      \textit{If a change is made to a system at equilibrium, \\the system will partially oppose this change \colorbox{important}{if it is possible}}
    \item Accuracy of graph drawing - \colorbox{important}{use \textbf{clear} plastic ruler}
    \begin{itemize}\item Label vertical ratios\end{itemize}
        \item Use concentration table format for calculating equilibrium constant $K_C$
  \end{itemize}

  \begin{tcolorbox}[title=Important, colback=BurntOrange]
    \centering
    $K_C$ is \textbf{not} related to the rate of reaction\\
    $\implies$ we cannot say how fast a reaction os going to occur from the $K_C$ value
  \end{tcolorbox}

  \subsection{Exothermic \& endothermic reactions}

  \begin{itemize}
    \item All combustion reactions are exothermic
    \item Data book: molar heat of combustion $= |\Delta H|$
    \item Endothermic reactions rarely occur naturally (creates instability/entropy)
    \item $E_A=|E_{\text{max}}-E_{\text{initial}}|$
    \item \colorbox{important}{If coefficients of a thermochemical equation are changed, $\Delta H$ also changes}
    \item Possible data discrepencies in theoretical results:
      \begin{itemize}
        \item State of \ce{H2O}
        \item Incomplete combustion
        \item Heat loss to environment
      \end{itemize}
    \item \colorbox{important}{Analogy with simultaneous equations}
    \item Calorimetry - \colorbox{important}{insulate \textit{sides} of can not bottom.} Be specific.
  \end{itemize}
  Multiple choice question examples (features of \textbf{exothermic} reactions):
  \begin{enumerate}[label={\alph*)}]
    \item Products are \rule{4em}{0.5pt} as they have less chemical energy than reactants \hfill \textit{(more stable)}
    \item \rule{5em}{0.5pt} required to break bonds in products compared to reactants \hfill \textit{(more chemical energy)}
  \end{enumerate}
  Multiple choice question examples (features of \textbf{endothermic} reactions):
  \begin{enumerate}[label={\alph*)}]
    \item Transformation of \rule{4em}{0.5pt} energy from surroundings into \rule{4em}{0.5pt} \hfill \textit{(thermal, chemical)}
    \item $\therefore$ Surroundings and reaction becomes \rule{4em}{0.5pt} \hfill \textit{(colder)}
  \end{enumerate}

  \section{Oxidation numbers (memorise)}

  \renewcommand{\arraystretch}{1.4}
  \begin{tabularx}{0.8\textwidth}{r|X}
    \textbf{Species} & \textbf{Rule} \\
    \hline
    Elements & Always 0 \\
    Ions & Same as common ion \\
    Hydrogen & +1 (unless present as \ce{H2O} - O.N. = 0; or as hydride - O.N. = -1) \\
    Oxygen & -2 (unless present as \ce{O2} - O.N. = 0; or as peroxide - O.N. = -1) \\ 
    Molecules & Sum of O.N. must equal zero \\
    Molecular ions & Sum of O.N. must equal overall charge on ion
  \end{tabularx}

  \section{Redox reactions}
  \begin{itemize}
    \item Verify  equations: check charge of each side independently: charge(LHS) $=$ charge(RHS)
    \item Electrochemical series always has \colorbox{important}{oxidants} on left
    \item Top left and bottom right always react spontaneously
    \item For electrochemical cell questions: first parts are important, no consequential marks
    \item Non-standard conditions can alter positions of half-equations on electrochemical series and change $E^0$ values
    \item Secondary cells - polarity is constant, but reaction at each electrode swaps
  \end{itemize}

  \subsection{Galvanic cells}
  \begin{itemize}
    \item Value of $E^0$ is \textit{not} a reliable indicator for rate of reaction
    \item Half cells are physically separate
    \item \colorbox{important}{Products must remain in contact with electrodes}
  \end{itemize}

  \subsection{Electrolytic cells}
  \begin{itemize}
    \item Possible question: name observations
      \begin{itemize}
        \item Bubbles
        \item \ce{O2} would \textit{not} be visible
        \item Cannot \textit{see} $\uparrow [$\ce{H+}$]$
        \item Can see \ce{Cu(s)} deposit on electrode
        \item Can see colour change (pH) - \ce{Cu2+} solution can be an indicator
      \end{itemize}
    \item Less side reactions in e.g. lithium ion cells (efficiency)
    \item Lower reactions in electrochemical series do not occur forwards (L$\rightarrow$R)
    \item Check state of \ce{H2O} - can it be liquid at that temperature?
  \end{itemize}

  \subsection{Fuel cells}
  \begin{itemize}
    \item Galvanic cells are primary cells, fuel cells are not primary \colorbox{important}{are they secondary?}
    \item Major disadvantage of fuel cells: expensive electrodes (they must also function as catalysts)
    \item Fuel cells - same overall reaction as combustion
    \item Reactangs must not come into contact
    \item Highly efficient
  \end{itemize}

  \subsection{Electrochemical series}
  
  \begin{tcolorbox}[colback=SkyBlue]
    \centering
    Strongest oxidant will always react preferentially with best reductant\\
    Always identify \textit{all} chemicals present in reaction on electrochemical series
  \end{tcolorbox}

\end{document}
