Preparation of Solutions in the pH Range of Approximately -47 to +47 Suppose we have a 11 solution which is lo-' M in HCI. Assuming that HCI is 100% dissociated, [HaO+l = 10-6 M and the p H is 6. Now add enough pure water (about 90 I) to make the total volume of acid solution equal to 100 1. Then [HaO+l = lo-' M and p H = 8. By adding more and more water one can obtain as high a p H as desired. Althoush in principle one could reach a p H of infinity by this procedure, in practice one is limited by the finite supply of available water. Assuming that the earth's st,orehouse of water is about 10P81,the maximum p H obtainable would be that of a. solution containing but a single molecule of HC1 in l o a a1 of water. For this solution [H.O+] = (1/6.02 X 1023molesHCL)/10*31= 1.7 X 10-"dfso t h a t p H = 46.8. Alkaline solutions with p H above 12 are known to attack ordinary glass quite readily so that some careful thought would have to be given to the storage of such ultra-alkaline preparations. I t should be fairlv obvious that a ~roceduresimilar to that described above could be used to heg.t~-n ~ t h3 d i h i e p r r p n iultrn-widic colutim+, i.e., .dutic.nr w l h very Ion p l l . t h w .icn~~Iy Ia,e m d add3 W : ~ I ~ V . The prwric:tl limit wm~lube around .I pli < 1 -.t6.> ' 1 ' 1 ~; i r ~ r ~ ~ ~ v etnit , - 1 1 . t ~ m ~ t h ~reAJ+s sl i n it.* u t ~ l i m ~ id~ w r y i t . t x p ~ n . ~ w ~ I I : I I C I Kmki!.ly ~ ~ . . pwe w:trm m d v3n1-11ingly small amounts of conventional acids and bases.
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Journol o f Chemical Education
