Thermodynamics

Consider the reaction 2H2S(g) + 3O2(g) 2H2O(l) + 2SO2(g) The magnitude of enthalpy change for the reaction in kJ mol-1 is . (Nearest integer) Given : f H (H2S) = -20.1 kJ mol-1 f H (H2O) = -286.0 kJ mol-1 f H (SO2) = -297.0 kJ mol-1

Arrange the following isothermal processes in order of the magnitude of the work (p − V) involved between states 1 and 2. Choose the correct option.

1. |wB| > |wA| > |wC| > |wD|
2. |wC| > |wD| > |wA| > |wB|
3. |wC| > |wD| > |wB| > |wA|
4. |wB| > |wA| > |wD| > |wC|

Consider the reaction X Y at 300 K. If H and K are 28.40 kJ mol-1 and 1.8 10-7 at the same temperature, then the magnitude of S for the reaction in J K-1 mol-1 is . (Nearest integer) (Given : R = 8.3 J K-1 mol-1, ln 10 = 2.3, log 3 = 0.48, log 2 = 0.30)

Match List - I with List - II. Given V1 and V2 are initial and final volumes respectively. Choose the correct answer from the options given below :

1. A-II, B-III, C-I, D-IV
2. A-II, B-I, C-IV, D-III
3. A-II, B-I, C-III, D-IV
4. A-I, B-II, C-III, D-IV

Consider the following data for the reaction X2(g) + Y2(g) 2XY(g) at 600 K. The rG (in kJ mol-1) for the reaction is : array|c|c|c| Compound & fH 600 K ( kJ mol-1) & S 600 K ( J mol-1 K-1) \ XY(g) & 42 & 200 \ X2(g) & 8 & 140 \ Y2(g) & 80 & 250 \ array

1. −21000
2. −10
3. −1000
4. −9.012

The correct order of molar heat capacities measured at 298 K and 1 bar is :

1. Copper(s) > Bromine(l) > Helium(g)
2. Bromine(l) > Copper(s) > Helium(g)
3. Helium(g) > Bromine(l) > Copper(s)
4. Helium(g) > Bromine(l) = Copper(s)

Given below are two statements : In the light of the above statements, choose the correct answer from the options given below

1. Both Statement I and Statement II are true
2. Both Statement I and Statement II are false
3. Statement I is true but Statement II is false
4. Statement I is false but Statement II is true

If 3.365 g of ethanol (l) is burnt completely in a bomb calorimeter at 298.15 K, the heat produced is 99.472 kJ. The | Hf | of ethanol at 298.15 K is 102 kJ mol-1. (Nearest integer) Given: Standard enthalpy for combustion of graphite = −393.5 kJ mol-1 Standard enthalpy of formation of water (l) = −285.8 kJ mol-1 Molar mass in g mol-1 of C, H, O are 12, 1 and 16 respectively

Consider the following data. (i) 2Al(s) + 6HCl(aq) Al2Cl6(aq) + 3H2(g) + 1200 kJ/mol (ii) H2(g) + Cl2(g) 2HCl(g) + 164 kJ/mol (iii) HCl(g) + aq HCl(aq) + 83 kJ/mol (iv) Al2Cl6(s) + aq Al2Cl6(aq) + 663 kJ/mol The enthalpy of formation of anhydrous solid Al2Cl6 is :

1. -648 kJ mol-1
2. -1350 kJ mol-1
3. -2002 kJ mol-1
4. -1527 kJ mol-1

At the transition temperature T, A B and G = 105 - 35 T where A and B are two states of substance X. The transition temperature in °C when pressure is 1 atm is . (Nearest integer)

Gas 'A' undergoes change from state 'X' to state 'Y'. In this process, the heat absorbed and work done by the gas is 10 J and 18 J respectively. Now gas is brought back to state 'X' by another process during which 6 J of heat is evolved. In the reverse process of 'Y' to 'X',

1. 18 J of the work is done by the gas 'A'.
2. 2 J of the work is done by the gas 'A'.
3. 12 J of the work is done on the gas 'A' by the surrounding.
4. 14 J of the work is done on the gas 'A' by the surrounding.

20.0 dm3 of an ideal gas 'X' at 600 K and 0.5 MPa undergoes isothermal reversible expansion until pressure of the gas is 0.2 MPa. Which of the following option is correct? (Given: 2 = 0.3010 and 5 = 0.6989)

1. w = -9.1 kJ, U = 0, H = 0, q = 9.1 kJ
2. w = 9.1 J, U = 9.1 J, H = 0; q = 0
3. w = -3.9 kJ, U = 0, H = 0; q = 3.9 kJ
4. w = +4.1 kJ, U = 0, H = 0; q = -4.1 kJ

The plot of 10 K vs 1T gives a straight line. The intercept and slope respectively are (where K is the equilibrium constant).

1. - S R2.303, H R2.303
2. - H 2.303R, S 2.303R
3. S 2.303R, - H 2.303R
4. 2.303R H , 2.303R S

Match the LIST-I with LIST-II Choose the correct answer from the options given below:

1. A-IV, B-I, C-III, D-II
2. A-I, B-III, C-II, D-IV
3. A-II, B-I, C-III, D-IV
4. A-IV, B-II, C-III, D-I

The heats of atomisation of methane and ethane are 'x' kJ mol-1 and 'y' kJ mol-1 respectively. The longest wavelength ( ) of light capable of breaking the C-C bond can be expressed in SI unit as :

1. NA hc250(y - 6x)
2. NA hc (y - 6x4 )-1
3. hc1000 ( y - 6x4 )-1
4. NA hc250(4y - 6x)

A cup of water at 5 C (system) is placed in a microwave oven and the oven is turned on for one minute during which the water begins to boil. Which of the following options is true?

1. q = +ve, w = -ve, U = +ve
2. q = +ve, w = 0, U = -ve
3. q = +ve, w = -ve, U = -ve
4. q = -ve, w = -ve, U = -ve

Match the LIST-I with LIST-II Choose the correct answer from the options given below :

1. A-I, B-II, C-III, D-IV
2. A-III, B-II, C-IV, D-I
3. A-II, B-I, C-III, D-IV
4. A-II, B-III, C-I, D-IV

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

Consider the given data : (a) HCl(g) + 10H2O(l) HCl 10H2O; H = -69.01 kJ mol-1 (b) HCl(g) + 40H2O(l) HCl 40H2O; H = -72.79 kJ mol-1 Choose the correct statement :

1. The heat of dilution for the HCl (HCl 10H2O to HCl 40H2O) is 3.78 kJ mol-1.
2. Dissolution of gas in water is an endothermic process.
3. The heat of solution depends on the amount of solvent.
4. The heat of formation of HCl solution is represented by both (a) and (b).

Which of the following properties will change when system containing solution 1 will become solution 2 ? [figure]

1. Molar heat capacity
2. Concentration
3. Gibbs free energy
4. Density

Given : sub H [C (graphite)] = 710 kJ mol-1 C-H H = 414 kJ mol-1 H-H H = 436 kJ mol-1 C=C H = 611 kJ mol-1 The f H for CH2=CH2 is kJ mol-1 (nearest integer value)