Question

How much heat will be required to make `2kg` of calcium carbide `(CaC_(2))` according to the following reaction?
`CaO(s) +3C(s) rarr CaC_(2)(s) +CO(g)`
The heats of formations of `caO(s), CaC_(2)(s)`, and `CO(g)` are `-151.0,-14.0`,and `-26.0 kcal`, respectively.

Answer 1

`DeltaH=sumDeltaH_(f("products"))^(@)-sumDeltaH_(f("reactants"))^(@)`
`=[DeltaH_(f(CaC_(2)))^(@)+DeltaH_(f(CO))^(@)][DeltaH_(f(CaO))^(@)+3DeltaH_(f(c))^(@)]`
`=[-14.2-26.4]-[-151.4+3xx0]`
`=40.6+151.6=111.0kcal`
For formation of 64g of `CaC_(2)` 111.0 kcal of heat is required so, heat required for making 2000 g of
`CaC_(2)=(111.0)/(64)xx2000=3468.75kcal`