Joseph M. Walsh
College o f Sonta Fe Sonto Fe, N e w Mexico 87501
A Simple Colorimetry Apparatus
A simple nppnrntus to improve the technirl~wnnd results in nn introth~ctoryrxprriment in mlorimetry is hrrr presrntd. Thc construction drtnils nrr shown in t h r nccompnnyingfigurr. T h r hnck-honrd rvnn mnclr of I/,-in. prrsrrrl lmnrcl; t h r c o l ~ ~ n mrrr ~ n s of soft pine, nnd t h e trnnspnrrnt hnsr \vns n stnnclnrtl micrnscope slidr gluw1 to thc c o l ~ ~ m nnnd s protrrted from ncridentnl hrr:tkngr hy hring rovrrnl on t h r outsidr with trnnspnrrnt plnstie tnpr. The srnlr on the hnrk-honrd Jvns nindr hy inking in n p p r o p r i t ~ linw t ~ on graph pnper nod mnliing wrrrnl ropirs on n S r r o x mnchinr. T h r scnlr wns c o v r r l with crllophnnr to protrrt it from ncriclentnl spillngr d u r i n ~rxprrimrnts. Shrll vinls (84rnm sixr: 25 nun X 95 mm; liimhle #fiW.?O) were nsnl rind t h n c drtrrminwl the d i m r ~ ~ s i o n s of t h r nppnrntus. T h r flnt hnsw of the \ i n k nlong with thrir rnthrr uniform thicknew give prnctienlity to this nrrnngemrnt. In nctr~nlrxperimmts the stu+?ntr t r n n s f r r r l stnn-
dnrd nnd rmknon-n ~olutionshy menns of plnstic socln strnrvs used ns "pipets." T o prrvrnt eonfwion, t h r right hnnd vinl wns the stnndnnl (9) nnd t h r Irft hnncl v i d , the ~ ~ n k n o w( S n ) . T h r symbols (S) nnrl ( S )wrrp printwl on the npproprintr lmsls. The nppnrntus with t h r r i n k rontnining t h r solutions \\.err plnewl ovrr "light-l)oxrs"-fl~~orwrrt~thr~lhsor incnndrsrrnt lamps in :I simple hnx r o r r r n l with froslnl plnss. The vit~ls were hrld in thenppnrntus hy nn rlnutir hnnd. T h r r r s ~ ~ lfrom t s nn rxprrimrnt. I I S ~ I I Kropprr s111fntr solutions inclicnt~lthnt good ronsistrnt rwults cnn h r ohtninnl. T h r dxtn in t h r tnhlr nrr from o w srrtion of frrshmnn chrmistry s t ~ ~ d r n t s A . frw str~drnts rnc o r ~ n t r r lsrriow difficr~ltirsin mntrhing 1111. rolors. Thrir rrsults sho\vwI 3 - 4 0 ? vnrit~tion. S o t i r r t h r rwolta nl the rncl of l h r list i l l the tnhlr.
