Answer: The reaction [tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex] is classified as endothermic: heat is gained by the system.
Explanation:
A process or reaction in which heat is absorbed is called endothermic reaction.
For example, melting of ice is an endothermic process.
For an endothermic reaction the sign of [tex]\Delta H[/tex] is positive which means heat is gained by the system.
Here, the given reaction is as follows.
[tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex]
A process or reaction in which heat is released is called exothermic reaction.
For example, combustion reaction, freezing of water etc are exothermic process.
For an exothermic reaction the sign [tex]\Delta H[/tex] is negative which means heat is lost by the system.
Thus, we can conclude that the reaction [tex]SiO_{2}(g) + 3C(s) \rightarrow SiC(s) + 2CO(g); \Delta H = +624.7 kJ[/tex] is classified as endothermic: heat is gained by the system.