CHEM 1AA3 Chapter Notes - Chapter 14: Gas Constant, Intermediate 2, Intermediate 1
19 Sep 2013
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Document Summary
Chemical kinetics concerns how rates of chemical reactions are measured, how they can be. Chem 1aa3 predicted and how reaction-rate data are used to deduce probable reaction mechanisms. Rate = change in concentration of reactants and products over time. Rates are always positive: add a negative sign if using decrease of starting material to describe rate: average rate = - [a] / t. Stoichiometry is important: if a 2g: average rate = - [a] = [g] In general: aa + bb gg + hh, average rate = -1 [a] = -1 [b] = 1 [g] = 1 [h] = a t b t g t h t. Rate is change in concentration over time. Rates can change during a reaction, as seen in the food coloring exp. Many reactions may give an average rate of 1m/min for 1 min: average rate = 1m/min over first min for all 4 curves, average rates are of limited use prefer instantaneous rates.
