Thermodynamics · Question 17

If the enthalpy of sublimation of Li is 155 kJ mol-1, enthalpy of dissociation of F2 is 150 kJ mol-1, ionization enthalpy of Li is 520 kJ mol-1, electron gain enthalpy of F is -313 kJ mol-1, standard enthalpy of formation of LiF is -594 kJ mol-1. The magnitude of lattice enthalpy of LiF is kJ mol-1. (Nearest Integer)

Which of the following graphs between pressure 'p' versus volume 'V' represents the maximum work done?

1. [figure]
2. [figure]
3. [figure]
4. [figure]

Use the following data : array|c|c|c| Substance & f H (500 K) kJ mol-1 & S (500 K) J K-1 mol-1 \ AB(g) & 32 & 222 \ A2(g) & 6 & 146 \ B2(g) & x & 280 \ array One mole each of A2(g) and B2(g) are taken in a 1 L closed flask and allowed to establish the equilibrium at 500 K. A2(g) + B2(g) 2AB(g) The value of x (in kJ mol-1) is . (Nearest integer) (Given : K = 2.2, R = 8.3 J K-1 mol-1)

Consider the following data : f H (methane, g) = -X kJ mol-1 Enthalpy of sublimation of graphite = Y kJ mol-1 Dissociation enthalpy of H2 = Z kJ mol-1 The bond enthalpy of C–H bond is given by :

1. X+Y+2Z4
2. X+Y+4Z2
3. -X+Y+Z4
4. X+Y+Z

Resonance in X2Y can be represented as [figure] The enthalpy of formation of X2Y ( X X(g) + 12Y = Y(g) X2Y(g) ) is 80 kJ mol-1. The magnitude of resonance energy of X2Y is kJ mol-1 (nearest integer value). Given: Bond energies of X X, X = X, Y = Y and X = Y are 940, 410, 500, and 602 kJ mol-1 respectively. Valence X: 3, Y: 2

Total enthalpy change for freezing of 1 mol of water at 10 C to ice at -10 C is (Given: fusH = x kJ/mol Cp[H2O(l)] = y J mol-1 K-1 Cp[H2O(s)] = z J mol-1 K-1)

1. -x-10y-10z
2. x-10y-10z
3. -10(100x+y+z)
4. 10(100x+y+z)

The hydration energies of K+ and Cl- are -x and -y kJ/mol respectively. If the lattice energy of KCl is -z kJ/mol, then the heat of solution of KCl is :

1. x + y + z
2. z - (x + y)
3. -z - (x + y)
4. x - y - z

The correct statement amongst the following is :

1. The standard state of a pure gas is the pure gas at a pressure of 1 bar and temperature 273 K.
2. f H 500 is zero for O2(g).
3. f H 298 is zero for O(g).
4. The term 'standard state' implies that the temperature is 0°C.

One mole of an ideal gas expands isothermally and reversibly from 10 dm3 to 20 dm3 at 300 K. U, q and work done in the process respectively are Given: R = 8.3 J K-1 mol-1 10 = 2.3 2 = 0.30 3 = 0.48

1. 0, 21.84 kJ, -1.726 J
2. 0, 21.84 kJ, 21.84 kJ
3. 0, 1.718 kJ, -1.718 kJ
4. 0, -17.18 kJ, 1.718 J

Let us consider a reversible reaction at temperature, T. In this reaction, both H and S were observed to have positive values. If the equilibrium temperature is Te, then the reaction becomes spontaneous at:

1. Te > T
2. T > Te
3. T = Te
4. Te = 5T