chemistry experiments for children

solution,shake,countthe drops, and record the result. By now you have a great
deal ofinformationon yourdatasheet.Compareall your results.
Results:Distilled water (test tubeNo.1)made suds very easily anddidn't
require manydropsof soap solutionor much shaking.Tap water (test tube
No.2)made suds easily or else not at all,dependinguponwhatpartof the
countryyou live in. The more minerals dissolved in your water, the less easily
suds form. The calciumbicarbonatesolution(test tubeNo.3)made very few
suds, and thosethatit did makedisappearedvery quickly. Theothercalcium
bicarbonatesolution(test tubeNo.4)made very good suds after you boiledit
and after a whiteprecipitateseparatedout. Themagnesiumsulfate solution
(test tubeNo.5)formed few suds. Theothermagnesium sulfate solution (test
tubeNo.6)made goods suds after you addedsodiumtetraborateorpotassium
carbonate.
You have beenexperimentingwith four different kinds of water. Distilled
water is chemically pure H20.Because itcontainsnoimpurities,it makes soap
suds very easily.Tapwater ishardor soft,dependingon whether there are many
minerals in the soil near yourhomeor near the source of water foryourcity.
Ifit made no suds orpoorsuds, then itcontainedmany mineralsandconse-
quently was hard.Bicarbonatesdissolved in water make a special kind ofhard
water calledtemporaryhardwater. You can soften this type ofhardwater
simply by boiling it, as you did. Theequationshowing how theimpuritywas
forced out as aprecipitateis:.
Ca(HCOa) 2 ~Ca2COat+ H 20 + CO 2 t
Remember thatan arrow pointingupwardindicates a gas thathas been
released and an arrow pointingdownwardindicates aprecipitate.The Greek
letterdeltaover the arrow shows heat. Magnesiumsulfate also makes water
hard,butyoucan'tsoften this type ofhardwater by boiling it. You must add
anotherchemical to react with the sulfate impuritywhich prevents the soap
from forming suds. Sodiumtetraborateandpotassiumcarbonatearechemicals
thatwill do this. Here are theequationsshowing how they act:
MgS0 4 + Na2B 407 - MgB 407 + Na2SOv
MgS0 4 +K2COa- MgCOa+ KS0 4
Forindustrialuse, largequantitiesof water are softened by adding azeolite,
a specialcompoundforsofteningwater.