Notation for Order of Addition It is common practice to include in a chemical equation important experimental procedures and conditions affecting the outcome of a reaction. Conditions such as temperature, heat, solvent, catalyst, and reaction time are frequently noted above or below the arrow of an equation. Another important experimental condition that can affect the outcome of a reaction is the order in which reagents are added to each other. The notation described here will enable one to include in the chemical equation an implied statement regarding the order of addition. a) Let the slanted bracketd irepresent an upright reaction vessel. Reagents or special solvents already in this vessel
would be enclosed by these brackets. h) Let the slanted b r a c k e y jrepresent a vessel used for transferring a reagent into a receiving vessel. Reagents or special solvents already in this vessel would he enclosed by these hraekets. c ) When multiple sets of brackets are used, priority of addition will proceed from the innermost brackets. The following examples illustrate the use of the bracket notation: Exomple I . A must be added to B
-
rq+ B or A +LB& or /A] +LB]
(1) (2)
(3)
Although each equation implies the correct order of addition, the first or second equation would be preferred over the third equation because it is simplier. Example 2. A is added to B, then C is added to this mixture. C + P +[B])This example points out that with multiple sets of brackets priority of addition is given to the innermost brackets
r ~ +7 + o~A+B+Lc]-
Example 3. C i s added t o A, then this mixture is added to B.
[C
+ LA]^+ B
Example 4. A and B are added simultaneously to C.
rB7
C
Example 5. A mixture of A and B is added to C. ~ A + B ~ + C .Althl)uyhm.itll jwrnal. t h h inrcmmrlm, ns well u i t ~ m p e m t u r rr.t c . is rcitrmrrd in the ~ x p e r : n untal arttirm :I is advdnl:lynmturn rr.cdt.r 111 I ~ a l f o r d r dn lnryenmuunt ot inturrnauw m a hrrcf rratrmmt. I t ir.llst,nd\. ic.rarcsdrr 15, I,c ~ l o t c t~u lm?purtatnl wditi.m- allrainy the u ~ r r u m vot a rwctitw L'aing *u< h Y n.,rnrh,n i t , texts tlr alrttract* has even greater value since detailed experimental conditions are purposely avoided for the sake of brevity J. H. Niewahner Depanmenl ol Pnysca, Scences honnern KenlLchy -nwersry r( ghland ne ghlr. K Y 41076
Volume 58
Number 6
JOne 1981
461
