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Review of MgO, Properties 6 the system or only the small amount that is in solution as a function'of the solubility product. The point is that it is relatively constant in either case. The expression: -d [Mg02 ]Idt = d[02 ]/dt = kM, - k[02 ] [i0A]. will give first order Kinetics that are a function of the Oz concentration developed in the system. This was seen in our m,in work and the work at USC. If the concentration of oxygen is Dept essentially at zero, the expression is then: -d N902 ]!dt = d[02yd,= k1�i, [11} which will integrate as zero order kinetics. An interesting fe_':',a of the above is that if We add znothar mechanism for removing oxygen, e.g., bacts,ia, plant cells, etc., the picture does not change. To sae this, consider: 02 -> reM, OVal by another meth:nis,.m [12} This simply Gds another removal term to eq'J�;ion [10 A). so that: S -d(iV1gO2 ]Id! = dr02 }!dt = k1% - k[02 ] - k' 21 [13] where k' Is t�"l3 rate constant for equation (12). but, we Can Co:itJ1ne the Constanis til equation [13} as: -d[MgO2 )!dt = d102 }!dt = k,N.to - (k+k) [0, ] [14] and the new constant can be replaced by a single value since, if the reactions were occurring sim'�Itaneously, there would be no direct way of d:�:inguishing whether the constant measured was one of the sual of two. The we Would still sae first order kinetics. Thus, the oxygen leaving reaction [S] drives it to the right ii" can actually leave the system. This is one of the reasons we want s!o:v rebase. �'f: do not `+pant the oxygen to be released so fast that it exceeds the ability of water to ho':d it over long periods of tina (at equilibrium - `ve don'i care that water can hold 50 ppirl for short periods of time - plants and bacteria take a long time to grotiv and metaboliz-e - it is the long-term concentrations we are concerned with). • It should also benoted that oxygen in water can react to give small amounts of peroxide under the right conditions but even th:s would re-pct back again tivith either the Mg (OH)2 or MgO because of thermodynamics of t'na peroxide reactions.