Saved Bookmarks
| 1. |
1. Find the enthalpy of the reaction, C(graphite) + O2 (g) → CO2 (g) Given, (i) C(graphite)+ ½ O2(g) → CO2(g); ∆H =-110.5 kJ mol-1 (ii) CO(g) + ½ O2 (g) → CO2 (g); ∆H =-283.0 kJ mol-1 2. Melting of ice is a spontaneous process. What are the criteria for spontaneity of a process? |
|
Answer» 1. Consider the reaction, C(grahite) + O2 (g) → CO2 (g); ∆H = x CO2 can also be prepared through the following two steps: (i) C(graphite)+ ½ O2 (g) → CO(g); ∆H =110.5 kJ mol-1 (ii) CO(g) + ½ O2(g) → CO2 (g); ∆H =-283.0 kJ mol-1 Then by Hess’s law, x = (-110.5+-283.0) kJ = -393.5 kJ 2. Certain endothermic process are found to be spontaneous in nature. Hence, spontaneous behaviour of a process cannot be explained only on the basis of energy consideration. For a spontaneous process ∆STotal is +ve. For a nonspontaneous process ∆STotal is -ve. |
|