Q&A
GETTY IMAGES X3 ILLUSTRATION: DAN BRIGHT
WHAT’SHAPPENING
Thekeytohowthe‘lavalamp’worksis thefactthatoilandwaterdon’tmix.
Whethertwoliquidsmixdependsontheinteractionsbetweentheirmolecules
andalsotheirfreedomtomovearound– thestrongerthea ractiveforces,
andthegreaterthepossibilitiesofmovement,themorelikelytheyaretomix.
Watermoleculesare‘polar’– oneendis negativelycharged,andtheotheris
positivelycharged.Thismeansthatwatermoleculesa racteachothermore
stronglythantheya ractoilmolecules,whichare‘non-polar’.Also,the
watermoleculesendupforminga kindofcagearoundtheoilmolecules,
restrictingthemotionofboth.Thisis anunfavourablestate,andthe
waterandoilmoleculesquicklyseparate.Theoil oatsontopofthewater
becauseit is lessdense.
Thetabletscontaincitricacidandsodiumbicarbonate,whicharereleased
intothewaterwhenthetabletdissolves.Whenparticlesofthesetwo
chemicalscomeintocontactwitheachother,theyreact,producingcarbon
dioxidegas.Thegasformsbubblesinthewater.Thesearelessdensethan
boththewaterandtheoil,so oatupwards,draggingalongsomeofthe
colouredwater.Thebubblesburst once they reach the top of the oil, and the
water falls back down.AS
WHATTODO
1.Fillthecont ainerabout a third of the
wayupwithwater.
2.Pourcookingoilontopofthewater
untilthecontaineris nearlyfull.
3.Waitfortheoilandwatertoseparate.
4.Adda fewdropsoffoodcolouring
andwaitforthe water to become
coloured.
5.Breakthetabletinhalf and drop it
intothecontainer.
6.Watchthelavalampdoit sthing!
7.Addmorepiecesofthe t ablet to keep
the reaction going.
DIY
SCIENCE
HOMEMADE LAVA LAMP
WHATYOU’LL
NEED
Q Atall,open
container
suchasaplastic
drinks
bo leoraglass
QCookingoil
QWater
QFoodcolouring
QFizzyvitamin
tabletor
Alka-Seltzer