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DECOMPOSITIONREACTION
TASK1.2.
Purpose
Indecompositionreactions,onesubstanceundergoesareactiontoproduce
twoormoreotherproducts.Manycompoundsundergodecompositionreac-
tionswhentheyareheated.Howeasilydecompositionoccursdependsonthe
stabilityofthecompound.Forexample,carbonicacidinwatersolutionis
sounstablethatmostofitdecomposestocarbondioxideandwateratroom
temperature.Anotherexampleisthedecompositionofsodiumazide,NaN3,
whichisusedtoinflatecarairbags.Duringcollisionthecompounddecomposes
rapidly,forminggasnitrogenwhichexpandstheairbag.Onthecontrary,very
stablecompoundssuchasmanymetalcarbonates,water,sodiumchloridecan
onlybedecomposedbyheatingtohightemperature(CaCO3)orbypassingan
electricalcurrentintheprocesscalledelectrolysis.Theaimofthisexperiment
istogetfamiliarwithdecompositionreactionofsomesubstances.
Reagents:
solidcopper(II)
sulfatepentahydrate,CuSO4·5H2O
solidcobalt(II)
sulfateheptahydrate,CoSO4·7H2O
Experimentation:
nPlaceeachofthesubstancessuccessivelyinthetest-tube.Heatthetest-
tubeovertheflameholdingitbymeansofthetest-tubeclamp.Observe
thereactionoccurringduringheating.
nAfterfinishingthereactionleavethesubstancetocoolandpouritouton
thewatchglass.
nObservethesubstanceafterthereaction.Writedowntheobservationsin
thetable.
Laboratoryequipment:
3test-tubes
gasburner
glassspoon
test-tubeclamp
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