Carbide Cannons & Miners’ Lamps – The Chemistry?

Chemistry, Technology
When I was a kid, a friend showed me what he called an acetylene cannon. Many know it as a carbide cannon. What made it work? It's all a matter of chemistry. Which Carbide? A carbide is a compound in which carbon is bonded to a more electropositive element. Silicon carbide (SiC) and tungsten carbide (WC) are two well-known examples. What carbide do carbide cannons use? Calcium Carbide The answer is calcium carbide. Lime and coke are placed in an electric furnace. The chemical reaction is: CaO + 3 C → CaC2 + CO2↑ What makes calcium oxide so interesting is its bonding. The valence of calcium is +2. Ordinarily, carbon is assigned a valence of 4. Something's strange here... The puzzle is solved if we write the structure of…
Read More

Benzene from Coal and Lye?

Chemistry, Education
[caption id="attachment_17736" align="alignright" width="480"] Coal and Lye[/caption] As a youth, I read whatever chemistry books I could get hold of. One made reference to an obscure synthesis of the liquid aromatic compound benzene from coal and lye, by means of heat. This reaction would seem to be an improbable one. Can a stoichiometric equation be written for such a synthesis? The answer is, Yes. This in itself does not guarantee the reaction can actually take place. 6 NaOH + 9 C → 3 Na2O + C6H6 + 3 CO I learned of this synthesis from an old book, possibly published in the 1800s. Coal and Lye - What Conditions? Such a reaction strongly suggests isolation. The reaction required considerable heat. Also, air was to be excluded, since carbon would react…
Read More