1. Why is the enthalpy of sublimation is equal to the sum of enthalpy of fusion and enthalpy of vaporization?

2. Under what conditions of ΔG, ΔH or ΔS, a reaction will be spontaneous at all temperatures?

3. Why is the heat of neutralisation of a strong acid by a strong base is constant as 57.0 kJ / mole?

4. When does entropy increases in a reaction.

5. Entropy of the solution is higher than that of pure liquid, why?

6. The ΔG at m.pt. of ice is zero.

7. At temperature T, the endothermic reaction A ——> B proceeds almost to completion. WhyΔS is + ve ?

8. Why standard heat of formation of diamond is not zero though it is an element?

9. Can the absolute value of internal energy be determined? Why or why not?

10. Same mass of diamond and graphite (both being carbon) are burnt in oxygen. Will the heat produced be same or different? Why?

11. Why in chemical reactions generally heat is either evolved or absorbed?

12. Why is the enthalpy of sublimation equal to the sum of enthalpy of fusion and enthalpy of vaporisation?

13. When an ideal gas expands in vacuum, there is neither absorption nor evolution of heat. Why?

14. Calculate the heat change for the following reaction:

CH₄(g) + 2O₂(g) ———> CO₂(g) + 2H₂O(l)

for CH₄, H₂O and CO₂ are -17.89, -68.3 and -94.05 kcal/mole

15. The heat of reaction C(s) + 1/2 O2(g) ——> CO(g) at 17°C and at constant volume is -29.29 kcal. Calculate the heat of reaction at constant pressure.

16.Thermochemistry is the study of relationship between heat energy & ………………………..

17.Define Gibbs free energy.

18.Total energy for a reversible isothermal cycle is……………………………

19.Find out the value of equilibrium constant for the following reaction at 298 K.

2NH₃ (g) + CO₂(g) ——> NH₂CONH₂(aq.) + H₂O (l)

Standard Gibbs energy change Δr G^- at the given temperature is -13.6 kJ/mol.

20.What you can conclude from this graph

iqra butt , 14 Years ago

Grade