Thermodynamics

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

A perfect gas (0.1 mol) having Cv = 1.50 R (independent of temperature) undergoes the following transformation from point 1 to point 4. If each step is reversible, the total work done (w) while going from point 1 to point 4 is (-) J (nearest integer) [Given: R = 0.082 L atm K-1 mol-1] [figure]

A sample of n-octane (1.14 g) was completely burnt in excess of oxygen in a bomb calorimeter, whose heat capacity is 5 kJ K-1. As a result of combustion reaction, the temperature of the calorimeter is increased by 5 K. The magnitude of the heat of combustion of octane at constant volume is kJ mol-1 (nearest integer).

[figure] Two vessels A and B are connected via stopcock. The vessel A is filled with a gas at a certain pressure. The entire assembly is immersed in water and is allowed to come to thermal equilibrium with water. After opening the stopcock the gas from vessel A expands into vessel B and no change in temperature is observed in the thermometer. Which of the following statement is true ?

1. dq 0
2. The pressure in the vessel B before opening the stopcock is zero
3. dw 0
4. dU 0

Arrange the following in order of magnitude of work done by the system/on the system at constant temperature. (a) | wreversible| for expansion in infinite stages. (b) | wirreversible| for expansion in single stage. (c) | wreversible| for compression in infinite stages. (d) | wirreversible| for compression in single stage. Choose the correct answer from the options given below:

1. d > c = a > b
2. c = a > d > b
3. a > c > b > d
4. a > b > c > d

Which of the following graphs correctly represents the variation of thermodynamic properties of Haber's process?

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

500 J of energy is transferred as heat to 0.5 mol of Argon gas at 298 K and 1.00 atm. The final temperature and the change in internal energy respectively are: Given: R = 8.3 J K-1 mol-1

1. 368 K and 500 J
2. 348 K and 300 J
3. 378 K and 300 J
4. 378 K and 500 J

If C (diamond) C (graphite) + X kJ mol-1 C (diamond) + O2(g) CO2(g) + Y kJ mol-1 C (graphite) + O2(g) CO2(g) + Z kJ mol-1 at constant temperature. Then

1. -X = Y + Z
2. X = Y - Z
3. X = -Y + Z
4. X = Y + Z

The formation enthalpies, Hf for H(g) and O(g) are 220.0 and 250.0 kJ mol-1, respectively, at 298.15 K, and Hf for H2O(g) is -242.0 kJ mol-1 at the same temperature. The average bond enthalpy of the O-H bond in water at 298.15 K is kJ mol-1 (nearest integer).

[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→D→A as shown in the three cases above. Choose the correct option regarding U :

1. U(Case-III) > U(Case-II) > U(Case-I)
2. U(Case-I) > U(Case-II) > U(Case-III)
3. U(Case-I) = U(Case-II) = U(Case-III)
4. U(Case-I) > U(Case-III) > U(Case-II)

Consider the following data: Heat of formation of CO2(g) = -393.5 kJ mol-1 Heat of formation of H2O(l) = -286.0 kJ mol-1 Heat of combustion of benzene = -3267.0 kJ mol-1 The heat of formation of benzene is kJ mol-1. (Nearest integer)

Let us consider an endothermic reaction which is non-spontaneous at the freezing point of water. However, the reaction is spontaneous at boiling point of water. Choose the correct option.

1. Both and are (-ve)
2. is (+ve) but is (-ve)
3. is (-ve) but is (+ve)
4. Both and are (+ve)

Standard entropies of X2, Y2 and XY5 are 70, 50 and 110 J K-1 mol-1 respectively. The temperature in Kelvin at which the reaction 12X2 + 52Y2 XY5 H = -35 kJ mol-1 will be at equilibrium is (Nearest integer)

S(g)+ 32O2(g) SO3(g)+2x kcal SO2(g)+ 12O2(g) SO3(g)+y kcal The heat of formation of SO2(g) is given by :

1. 2x+y kcal
2. 2xy kcal
3. y-2x kcal
4. x+y kcal

Which of the following mixing of 1 M base and 1 M acid leads to the largest increase in temperature?

1. 50 mL HCl and 20 mL NaOH
2. 30 mL HCl and 30 mL NaOH
3. 45 mL CH3COOH and 25 mL NaOH
4. 30 mL CH3COOH and 30 mL NaOH

Ice at -5 C is heated to become vapor with temperature of 110 C at atmospheric pressure. The entropy change associated with this process can be obtained from

1. 268 K273 K Cp,m dT + Hm, fusionTf + Hm, vaporisationTb + 273 K373 K Cp,m dT + 373 K383 K Cp,m dT
2. 268 K383 K Cp dT + Hmelting273 + Hboiling373
3. 268 K383 K Cp dT + qrevT
4. 268 K273 K Cp,mT dT + Hm, fusionTf + Hm, vaporisationTb + 273 K373 K Cp,m dTT + 373 K383 K Cp,m dTT

The standard enthalpy and standard entropy of decomposition of N2O4 to NO2 are 55.0 kJ mol-1 and 175.0 J/K/mol respectively. The standard free energy change for this reaction at 25 in J mol-1 is (Nearest integer)

The effect of temperature on spontaneity of reactions are represented as : [figure] The incorrect combinations are :

1. A and C only
2. B and D only
3. A and D only
4. B and C only

The bond dissociation enthalpy of X2 H bond calculated from the given data is kJ mol-1. (Nearest integer) M+X-(s) M+(g)+X-(g) H lattice=800 kJ mol-1 M(s) M(g) H sub=100 kJ mol-1 M(g) M+(g)+e-(g) H i=500 kJ mol-1 X(g)+e-(g) X-(g) H eg=-300 kJ mol-1 M(s)+ 12X2(g) M+X-(s) H f=-400 kJ mol-1 [Given : M+X- is a pure ionic compound and X forms a diatomic molecule X2 in gaseous state]

A liquid when kept inside a thermally insulated closed vessel at 25 was mechanically stirred from outside. What will be the correct option for the following thermodynamic parameters ?

1. U = 0, q < 0, w > 0
2. U > 0, q = 0, w > 0
3. U = 0, q = 0, w = 0
4. U < 0, q = 0, w > 0

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

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

Consider the following cases of standard enthalpy of reaction ( Hr in kJ mol-1) C2H6(g)+ 72O2(g) 2CO2(g)+3H2O(l) H1 =-1550 C(graphite)+O2(g) CO2(g) H2 =-393.5 H2(g)+ 12O2(g) H2O(l) H3 =-286 The magnitude of H f C2H6(g) is kJ mol-1 (Nearest integer).

When equal volume of 1 M HCl and 1 M H2SO4 are separately neutralised by excess volume of 1M NaOH solution. x and y kJ of heat is liberated respectively. The value of y/x is .

The heat of solution of anhydrous CuSO4 and CuSO4 5H2O are -70 kJ mol-1 and +12 kJ mol-1 respectively. The heat of hydration of CuSO4 to CuSO4 5H2O is -x kJ. The value of x is . (nearest integer).

When Hvap = 30 kJ/mol and Svap = 75 J mol-1 K-1, then the temperature of vapour, at one atmosphere is K.

[figure] Consider the figure provided. 1 mol of an ideal gas is kept in a cylinder, fitted with a piston, at the position A, at 18°C. If the piston is moved to position B, keeping the temperature unchanged, then 'x' L atm work is done in this reversible process. x = L atm. (nearest integer) [Given : Absolute temperature = °C + 273.15, R = 0.08206 L atm mol-1 K-1]

vapH for water is +40.79 kJ mol-1 at 1 bar and 100 C. Change in internal energy for this vapourisation under same condition is kJ mol-1. (Integer answer) (Given R = 8.3 JK-1 mol-1)

An ideal gas, Cv = 52R, is expanded adiabatically against a constant pressure of 1 atm until it doubles in volume. If the initial temperature and pressure is 298 K and 5 atm, respectively then the final temperature is K (nearest integer). [ cv is the molar heat capacity at constant volume]

For the reaction at 298 K, 2A + B C, H = 400 kJ mol-1 and S = 0.2 kJ mol-1 K-1. The reaction will become spontaneous above K.

Given below are two statements: One is labelled as Assertion (A) and the other is labelled as Reason (R) In the light of the above statements, choose the correct answer from the options given below.

1. (A) is true but (R) is false
2. Both (A) and (R) are true and (R) is the correct explanation of (A)
3. Both (A) and (R) are true but (R) is not the correct explanation of (A)
4. (A) is false but (R) is true