does not look hot.Don'ttouchit for a while. When the glass is cool, cut the
ends with thetriangularfile to form two nozzles.Fire-polishbothends.
Place the coal on the pie pan and cover it with papertowels. Using the
hammer,smash it into small pieces. Make it almost as fine as powder. Fill the
test tubeabouthalfway with the powdered coal. Fit the nozzle into thestopper
as shown in thediagram,andaccordingtoyoursafety rules.
Heatthe coal over theburnerfor several minutes, then light the gas coming
from the nozzle.
Results: When you heated the coal, it gaveoirthe gases, mainlymethane
(CH 4 )andethane(C2H 6 ) ,thatweretrappedin it as it was formed in the earth.
This gaseous mixture burnedwith acharacteristicblue flame. Thematerial
whichremainedin the test tube is a form ofcarboncalledcoke.If there was
any sticky brownish substancethere, too, it was acombination ofcoal tar
products,which are the residueofcoalburnedin this way.
With the energyprovidedby sunlight, plants build up their own tissues out
ofminerals and water from theearthand from carbondioxide from the air.
These decayed planttissues in sunken forests become coal deposits, and the
elements which theycontainedpass into the coal. Coal is basicallycarbon,and
withouttheadditionalelements from theplanttissues it would be purecarbon.
When you heated the coal, theseotherelements were forced outofthe tube
throughthe nozzle in the form of a gaseous mixture. This is oneofseveral
gaseous mixtures used in gas stoves. When anindustrialcompanymanufactures
gas like this, it passes steam over the hot coal to make the process more efficient.
Theremaining"coal"is also sold as coke.