chemistry experiments for children

dry cell. You now havethisarrangementfrom left to right: 6-inch wire, dry cell,
4-inch wire, dry cell, 6-inch wire. Wrap one of the loose endsofwirearoundthe
threads(screw-type grooves)ofthe flashlight bulb. Be sure theconnectionis
very tight. In the remainingwire, make an S-shaped bendabout2 inches from
one end, sothatyou can rest it on the edge of ajar.Make a similar S-shaped
loop in the free endofthe wireconnectedto the dry cell. Check the diagram.
NowputbothS-shaped loops overthe edge of thejarcontainingsulfuric acid,
sothatbothwire ends are in the solution.Touchthe endoftheunconnected
wire resting in the sulfuric acidsolutionto the small knob at thebottomof the
bulb. Makea noteofwhat happensto the bulb.Repeatthisprocedurewith
eachofthe fiveotherjars. Wipe off the endsofthe wireswith adampcloth
every time yousubstitutea new solution.
Results:When you used the solutionsofsulfuric acid, acetic acid, sodium
chloride, and magnesium sulfate, the bulb lit up.Itdidnotlight up when you
used thestarchand salad oil.
In the cases where the bulb lit up, thesolutionswereelectrolyte s,thatis,
liquidsthatallow electricalcurrentto passthroughthem. Most acid, base, and
saltsolutionsare electrolytes.The four solutionsthatwere electrolytes served
tocompletethecircuit-thecontinuouspaththatelectricity follows from its
source (here, the dry cells) to theappliance(here, the flashlight bulb). In the
cases where the bulb did not light up, the liquids were not electrolytes. The
starchand salad oil were neither acids, bases, nor salts. Because electricity
could not passthroughthem, they broke the circuit instead ofcompleting it.
The electricity,therefore, failed to reach the bulb.