chemistry experiments for children

with adiametera little largerthanthediameterofa test tube. Putthis piece
ofpaperover the surfaceofthehydrogenperoxide. Now fill the covered test
tube withhydrogenperoxide and put it, upside down,throughthe hole in the
paper-coveredjar,as you did before.
Putall theapparatusin a sunny place and letitstandfor 2 hours. At the end
ofthis time, have a glowing splint ready, andholdingit in onehand,remove
oneofthe test tubes from itsjarwith yourotherhand. In removing it, keep the
mouthofthe tube covered with yourthumb.Takeyourthumboff themouth
ofthe tube, and quicklythrusta glowing splint into the test tube. Repeatthis
procedurewith theothertest tube.
Results:At the endof2 hours, gas had collected at the topofthe test tubes.
Therewas less gas in the test tube from thepaper-coveredjarthanin theother
test tube. When you put a glowing splint into the test tube from thejarexposed
to sunlight, the splintburstinto a white flame,provingthatthe gas inthattest
tube was oxygen. In theothertest tube, there was only a slightreactionto the
glowing splint.
The light energyofsunlightbreaks down the moleculesofhydrogenperoxide
anddetaches oneatomofoxygen. Theequationfor thisreactionis:
4H 202 sunlight)4H 20 + 202 t
Hydrogenperoxide is not the only chemical affected by light. You may have
noticedthatmany drugs and chemicals come in brown or blue glasscontainers.
These are the ones whose molecules are sensitive to light, and thedark-colored
glass prevents most light rays from reaching thecontentsof thejar.
(Mostofthe commercial hydrogen peroxide, sold for use as an antiseptic, is
a 3%solutionofperoxide in water, but it is called alO-volumesolution.That
meansthatfor every measured amountofhydrogenperoxide, the volume of
oxygen released will be 10 times as great as the volume of the originalhydrogen
peroxidesolution.)
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