Q.Write the equation for the industrial preparation of ethyne from calcium carbide, and state one major industrial use of ethyne.

Calcium carbide, itself manufactured by heating calcium oxide (quicklime) with coke in an electric furnace, reacts readily with water at room temperature: $\text{CaC}_2+2\text{H}_2\text{O} \rightarrow \text{Ca(OH)}_2+\text{C}_2\text{H}_2$ -- releasing ethyne gas and calcium hydroxide (slaked lime) as by-product. This is the classical industrial route to ethyne, ultimately starting from limestone and coal/coke. Ethyne's most familiar industrial use is as the fuel gas burned with oxygen in an oxy-acetylene torch: its combustion releases an unusually large amount of heat over a very small, concentrated flame area, reaching temperatures around $3000\,°\text{C}$, hot enough to melt and weld or cut through steel and other metals -- a direct consequence of …

Recall the specific calcium carbide + water reaction and balance it (2 water molecules per carbide); connect ethyne's high heat of combustion to …

Writing the wrong stoichiometry (forgetting the '2' before water); confusing calcium carbide's reaction with water (giving ethyne) wi …