From: Andrew Lorimer <andrew@lorimer.id.au>
Date: Tue, 17 Sep 2019 10:23:41 +0000 (+1000)
Subject: [chem] notes on isomerism
X-Git-Tag: yr12~27
X-Git-Url: https://git.lorimer.id.au/notes.git/diff_plain/b965fcb62fa0143a6709fc11a872ad5add1ea2dc

[chem] notes on isomerism
---

diff --git a/chem/organic-2.md b/chem/organic-2.md
index 10dff38..5616416 100644
--- a/chem/organic-2.md
+++ b/chem/organic-2.md
@@ -4,6 +4,7 @@ header-includes:
 - \usepackage{mhchem}
 - \usepackage{chemfig}
 - \usepackage{tabularx}
+- \usepackage{gensymb}
 ---
 
 # Organic Chemistry
@@ -54,12 +55,14 @@ Alkynes: \ce{C_{$n$} H_{$2n-2$}}
 
 ## Isomers
 
-* **Structural isomers** - same molecular formula, different arrangement  
+* **Structural isomers** - same molecular formula, different arrangement
+- **Positional isomers** - different position of functional group (affects polarity)
+- **Chain isomers** - affects boiling point (more branches $implies$ lower boiling point)
 * **Stereoisomers** - same structural configuration, different orientation  
-  * **Opotical isomers** - chiral centre, 4 groups bonded to C, non-superimposable mirror image
+  * **Optical/chiral isomers (enantiomers)** - chiral centre, 4 groups bonded to C, non-superimposable mirror image. Racemic mixture: 50/50 of each enantiomer. Affects optical polarity of light.
   * **Geometric isomers** - \ce{C=C} double bond, 2 groups bonded to carbon atoms
-    + **Cis** - same horizontal plane
-    + **Trans** - diagonal
+    + **Cis** - same horizontal plane (symmetrical)
+    + **Trans** - diagonal (asymmetrical)
 
 \begin{center}\setlength\tabcolsep{1cm}
 \begin{tabularx}{0.5\textwidth}{cc}
@@ -68,6 +71,10 @@ Alkynes: \ce{C_{$n$} H_{$2n-2$}}
   \chemfig{[:60]{\text{\color{blue}R$^\prime$}}-C(-[:120]{\text{\color{red}R}})=[0]C(-[:-60]{\text{\color{red}R}})-[:60]{\text{\color{blue}R$^\prime$}}}
 \end{tabularx}\end{center}
 
+## Flash point
+
+Lowest temperature at which the liquid gives off enough vapour to be ignited. Flammable $\implies$ flash point > 37.8 \degree C.
+
 ## Reactions
 
 **Cracking** - split moluecules with heat/pressure/catalyst
@@ -106,3 +113,19 @@ Alkynes: \ce{C_{$n$} H_{$2n-2$}}
 - **Condensation reactions** (esterification): \ce{RCOOH + R^{$\prime$}OH -> RCOOR^{$\prime$} + H2O}
 - This is reversed by **hydrolysis**: ester + water $\rightarrow$ carboxylic acid + alcohol
 - Polyesters
+
+## Summary of reactions
+
+\textbf{Combustion:} \ce{C_{$x$} H_{$y$} + $z$O2 -> $x$CO2 + {$\dfrac{y}{2}$} H2O} \quad where $z=x+\dfrac{y}{4}$
+
+\textbf{Substitution:} e.g. halogenation/chlorination, catalysed by UV (alkanes) or compounds (alcohols etc.) which creates free radicals (unpaired e-)
+
+\textbf{Addition:} \ce{C=C} bond is broken, catalyst is required
+
+\textbf{Addition polymerisation:} uses addition to form a polymer
+
+\textbf{Condensation polymerisation:} produces \ce{H2O}
+
+\textbf{Oxidation:} occurs in alcohols to form aldehydes with catalysts \ce{H+/MnO4- (aq)} or \ce{H+/Cr2O7{2-} (aq)} - see combustion equation
+
+\textbf{Cracking:} heat/pressure/catalyst to break molecules
diff --git a/chem/organic-2.pdf b/chem/organic-2.pdf
index 3578123..8289c1a 100644
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