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Review of Mg02 Properties 2 . Destructive testing of samples is reasonable when the samples are only being . analyzed for total oxygen content. To understand what is going on, Nve need to understand t1he thermodynamics and the kinetics of the reactions of interest. While thermodynamics provides no information on hovr fast a reaction will go (that' is the province o; kinetics), it does tell us vihat the equilibrium dis`,ribution of products will be whin the reaction is finished. We cannot change that equilibrium distribution with catalysts. We can only change the time it takes to get to the equilibrium distribution. We can, ho%vever, dislurb the equilibrium distribution by removing one of the products or one of the in`_,mediates. So, for example, if the reaction releases oxygen and we remove oxygen from the system, the disappearance of reactants can be linked to the rate at ..,hidin oxygen is removed. We will see tinat in systems v;here fine oxygen concentratiori is only reduced slowly. first order kinetics for the disappearance of Mg02 is sten (their ofrelease is proportional to the amount of 1.'1,902 remaining), .-;inila in sys=_.-ns v,-here it is removed rapidly, one seas zero order kinetics Where the rase of releai-_ is linear. We prepare N1100, several v;2ys and I v;ill only c;scu_s one c them for clarity, but tine . argument is the s=me for the 0:hers. NIgo H2O2 - f"t-a02 = H2O (1 Notice that this re:-tion is v;ritten with a single e,rov; poi,n;i,= in tine direction v;e expect it to go. In general, one, v.rites reactions as an equilibrium: tA:)0 - H2O2 - MaO, H2O (?i One is only jist:fled in v;r it,ng the reaction as in Viine,n wn- is ov/ that the reaction proceeds virtually totally in that direction. Chemnists use rea. i-,ns for syn:nesis that proceed in the direction they vAsh them to proceed end it is possible to determine ahead of time, from the I ws of thermodynarnics, v;hich \%,Ey tha reaction v;ill proceed. i For any reaction, one can calculate a function cz-Hed the "G:bo's free energy." There is also a Helmholtz free energy function which is usually designa:ed by the letter A. Without going into unnecessary detail, I will mention for tine record that thea are several ways to use these free energy functions and sever ai s':_--:es that one can use as j reference St2te. The usefulness of thermodynamics is b2seJ on tine existence of "state . functions" such 2s the Gibb's free energy, the enthalpy, ani the entropy vrhich are related to a "system" by specifying the pressure, tine tempe,a::-ire, the volume and the composition. i