chemistry experiments for children

Allow most of the liquid to boil away.Notethe colorofthe liquid collected in
thejar.
Results: As the liquid boiled, the color becamedarker. As itevaporated,
steam formed and thequantityofwater in the flask decreased. The steam went
throughthe glasstubingto thepintjarembeddedin ice. Thesuddenchange in
temperaturemade the steam condense into water. The water in thejarwas
colorless.
Indistillation, evaporationoccurs first. This means thatwhen the boiling
liquid reached2lrF., the boilingpointofwater, the moleculesofwaterjumped
off the surface in the form of invisible water vapor. When these molecules
reached the ice-coldjar,theirtemperaturequickly went down, and they changed
back to liquid water.Allthe moleculesofsodiumchloride, sucrose, andcopper
sulfate remained in the flask. Each of thesesubstancesevaporatesat a different
temperature,and alloftheirevaporatingtemperaturesare much higherthan
thatofwater. This makesdistillationan easy way to separatesolidcontami-
nants from water. Unfortunately, the process would be too slowand too
expensive to use in large cities, whereenormousquantitiesofpurifiedwater
are needed.
Distilled water is used in filling medicalprescriptions,inbatteries,in steam
irons, and wherever else lOOper cent chemically purewateris required.
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HOW YOU CAN CHANGE HARD WATER TO SOFT WATER
Gather thesematerials:Distilled water (H20);ordinarytapwater (H 20 with
impurities); soap; calcium bicarbonate (Ca(HC0 3 ) 2) ; magnesium sulfate
(MgS0 4 ) ; sodium tetraborate (Na2B 407 ) or potassium carbonate(K2C0 3 ) ;
6 testtubes;a test tuberack;a test tubeholder;analcoholburner;aquart
jar;and an eyedropper.