Question

For a reaction,
`CaCO_(3(s)) rarr CaO_((s))+CO_(2(g))`
`Delta_(f)H^(@)(CaO)=-"631.1 kJ mol"^(-1)`
`Delta_(f)H^(@)(CO_(2))=-"393.5 kJ mol"^(-1) and`
`Delta_(f)H^(@)(CaCO_(3))=-"1206.9 kJ mol"^(-1)`
Which of the following is a correct statement?
A. A large amount of heat is evolved during the decomposition of `CaCO_(3)`.
B. Decomposition of `CaCO_(3)` is an endothermic process and heat is provided for decomposition
C. The amount of heat evolved cannot be calculated from the data provided .
D. `Delta_(f)H^(@)=SigmaDelta_(f)H^(@)" (reactants)"-Sigma Delta_(f)H^(@)" (products)"`

Answer 1

Correct Answer - B
`Delta_(r)H=Sigma_(f)H_(p)^(@)-SigmaDelta_(f)H_(R)^(@)`
`=[-635.1+(-393.5)]-[-1206.9]=+178.4kJ`