Seeing Reaction Mechanisms

The new techniques of femtosecond spectroscopy and STM are revolutionizing the way chemistry is carried our. We are now at the point where we can see rhe detailed pathways of chemical reactions.  

The STM images of the reaction of CO and 02. (a) An 02 molecule (oval) and a CO molecule (circle) on a surface. As the two molecules approach each other, a reaction occurs (b) to form a 0—CO—0 complex (c). After an electron pulse is applied to the complex, a newly formed C02 molecule exits the surface, leaving behind a single 0 atom (d). 

Now we substitute the expression for 0] into the rate law for the second step  

This rate law, derived by postulating the two elementary steps and making assumptions about the relative rates of these steps, agrees with the experimental rate law. Since this mechanism (the elementary steps plus the assumptions) also gives the correct overall stoichiometry, it is an acceptable mechanism for the decomposition of ozone to oxygen. 

The gas-phase reaction of chlorine with chloroform is described by the equation 

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Matrix-assisted laser desorption-ionization (MALDI) (Section 9.18A) A method in mass spectrometry for ionizing analytes that do not ionize well by electrospray ionization. The analyte is mixed with low molecular weight organic molecules that can absorb energy from a laser and then transfer this energy to the analyte, producing +1 ions which are then analyzed by the mass spectrometer. Mechanism (See Reaction mechanism)... 

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