Thermodynamics

The heat of combustion of solid benzoic acid at constant volume is -321.30 kJ at 27 C. The heat of combustion at constant pressure is (-321.30 - xR) kJ, the value of x is .

Combustion of 1 mole of benzene is expressed as C6H6(l) + 152O2(g) 6CO2(g) + 3H2O(l). The standard enthalpy of combustion of 2 mol of benzene is −'x' kJ. x = . Given : 1. Standard Enthalpy of formation of 1 mol of C6H6(l), for the reaction 6C(graphite) + 3H2(g) C6H6(l) is 48.5 kJ mol-1. 2. Standard Enthalpy of formation of 1 mol of CO2(g), for the reaction C(graphite) + O2(g) CO2(g) is -393.5 kJ mol-1. 3. Standard Enthalpy of formation of 1 mol of H2O(l), for the reaction H2(g) + 12O2(g) H2O(l) is -286 kJ mol-1.

The enthalpy of formation of ethane (C2H6) from ethylene by addition of hydrogen where the bond-energies of C-H, C-C, C=C, H-H are 414 kJ, 347 kJ, 615 kJ and 435 kJ respectively is − kJ

Three moles of an ideal gas are compressed isothermally from 60 L to 20 L using constant pressure of 5 atm. Heat exchange Q for the compression is - Lit. atm.

Choose the correct option for free expansion of an ideal gas under adiabatic condition from the following :

1. q = 0, T = 0, w = 0
2. q = 0, T 0, w = 0
3. q 0, T = 0, w = 0
4. q = 0, T < 0, w 0

For a certain reaction at 300 K, K = 10, then for the same reaction is − 10-1 kJ mol-1. (Given R = 8.314 J K-1 mol-1)

Consider the following reaction at 298 K: 32O2(g) O3(g); KP = 2.47 10-29. rG for the reaction is kJ. (Given R = 8.314 JK-1 mol-1)

If 5 moles of an ideal gas expands from 10 L to a volume of 100 L at 300 K under isothermal and reversible condition then work, w, is −x J. The value of x is . (Given R = 8.314 J K-1 mol-1)

[figure] An ideal gas undergoes a cyclic transformation starting from the point A and coming back to the same point by tracing the path A B C A as shown in the diagram above. The total work done in the process is J.

Two reactions are given below: 2Fe(s) + 32O2(g) Fe2O3(s), H = -822 kJ/mol C(s) + 12O2(g) CO(g), H = -110 kJ/mol Then enthalpy change for following reaction 3C(s) + Fe2O3(s) 2Fe(s) + 3CO(g) is kJ/mol.

Which of the following is not correct?

1. G is positive for a spontaneous reaction
2. G is positive for a non-spontaneous reaction
3. G is zero for a reversible reaction
4. G is negative for a spontaneous reaction

Standard enthalpy of vapourisation for CCl4 is 30.5 kJ mol-1. Heat required for vapourisation of 284 g of CCl4 at constant temperature is kJ. (Given molar mass in g mol-1; C = 12, Cl = 35.5)

If three moles of an ideal gas at 300 K expand isothermally from 30 dm3 to 45 dm3 against a constant opposing pressure of 80 kPa, then the amount of heat transferred is J.

For a certain thermochemical reaction M N at T = 400 K, = 77.2 kJ mol-1, = 122 J K-1, log equilibrium constant (log K) is − 10-1.