THE EFFECT OF TEMPERATURE ON SOLUBILITY titen from: Kenneth A, Knlx, TIIIS JOURXAL, 16, 183 (1959) by F,B. Dutton ecked by: Vance Hamiltun, East Lansmg High School, M~diigan
ARATION
urated solution of Inangdnesc (11) sulfate is d a t 27'C by shaking 70 g h1nSO4 or 130 g 7HsO vith 100 g water rmit:~iriing:L few drops H2SOa. The dear solut,ion is decanted and stored st,opperd test tube or prcfer:~l~lyone which is ed ofT and is eonsequent,ly :I "prrinanent" drmon-
DEMONSTRATION
ink wystals of M I I S ( J ~ . ~ Hsrpamte ~O out if the is placed iri a mixt,urc~of silt and ice, Cpnn
hcat~ngto 27', complek solution take6 plaw and on further hmtmg above 2 i o , vhite MIISO~H20\eparatcs out REMARKS
This demonstration servos t,o illustrat~c bol,li the common increase of solubility ~vith an iricrease in temperat,ure and t,hc lcss common decrease in solubility with increasing tempcrat,urc (of a diffcreni hydrate) of the manganese salt. A solubility diagram is given in the original Kobe art,icle. See also BATEMAX, L. A., and F E R S ~ L I ~117, S ,C,, ,rHIs ~ J O ~ I C A14, I , 315 ~ (1937).
SURFACE TENSION
PREPARATION
Provide t,wo large l~cakers,one containing m k r , and e ot,her a suitable wrt,l,ing agent in appropriate ncmtration, such as a O.loh Awosol OT solution.
DEMONSTRATION
'owdered s ~ ~ l p his u rpourrd f r m hoth ~ h:mds into thr eakcrs simultmeously. It, is not v r t by the purc t,er but, ni~11rslike sand into t,he hcaker of water
REMARKS
M m y variations will occur to demonsLrators, inrludi~~g t . h ~~ i s eof st,ring ~vhich may be lowred s l o ~ l yonto t,lic: surfare of t,hc liquid in each beaker. It, xvill accumulate on t,he top of the pure water hut set,tlr rapidly in the ~vater containing the surfaec a ( 4 w agent,, This is t,rw also for tmlls of nvna l ~ s o r ~ ~ a(wtton n t ~ and, of (mirse, if one uses larger crnitainers, for ducks. .4not,her variat,ion is to add a drop of concentrated detwgrnt, solution to the beakcr containing the floating sulfur. The spread of i,he d? the falling sulfur "sno~vstorm" whirh occurs.
