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 

COcan 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.



Discussion

No Comment Found

Related InterviewSolutions