Thermodynamics Worksheet





Thermodynamics is a subject that deals with various accepts related to heat transformation, work done, radiation and effect on material bodies.  It shows how the system changes when they interact with each other or with their surroundings.

The first definition of thermodynamics was introduced by Scottish physicist Lord Kelvin in 1854.

Thermodynamics can be applied on various fields like Science and engineering. There are four laws of thermodynamics.

Here, you can find some questions related to “Thermodynamics” and their answers:

Questions:

1. The heat of combustion of substance used as a fuel is called its:

(a)    Change in internal energy

(b)   Enthalpy change

(c)    Calorific value

(d)   None of these

 

2. For which of the following reactions, will \Delta H be equal to \Delta U

(a)    2NO_2(g) \to N_2O_4(g)

(b)   H_2(g) + I_2 (g) \to HI(g)

(c)    2SO_3(g) \to 2SO_2(g) + O_2(g)

(d)   H_2(g) + 1/2 O_2 \to H_2O(l)

 

3. In which of the following reactions heat of neutralization has highest numerical value:

(a)    CH_3COOH and NaOH

(b)   NaOH and HCl

(c)    NH_4OH and CH_3COOH

(d)   NH_4OH and HCl

 

4. What would be the heat released when 0.5 mole of nitric acid solution is mixed with 0.2 mole of potassium hydroxide solution:

(a)    11.4 kJ

(b)   22.8 kJ

(c)    285.5 kJ

(d)   57.1 kJ

 

5. A cylinder of gas is assumed to contain 11.2 kg of butene. If a normal family needs 20000 kJ of energy per day for cooking how long will the cylinder last? (heat of combustion of butane 2658 kJ mol^{-1})

(a)    26 days

(b)   30 days

(c)    13 days

(d)   20 clays

 

6. Which is spontaneous change:

(a)    Flow of heat

(b)   Formation of barium sulphate from barium chloride and sodium sulphate (c)

(c)    Flow of water

(d)   All

 

7 In which of the following entropy decreases:

(a)    Crystallisation of sucrose from solution

(b)   Melting of ice

(c)    Vaporization of camphor

(d)   Rusting of iron

 

8. The entropy of vaporisation of liquid is 100 Jk^{-1}MOL^{-1}and it boils at 300 K. What is \Delta H_{vap}

(a)    3000 kJ mol^{-1}

(b)   30.0 kJ mol^{-1}

(c)    300 kJ mol^{-1}

(d)   3.0 Kj mol^{-1}

 

9. Which of the following is a closed system:

(a)    Water being heated in a beaker

(b)   Reaction of Zn with dil HCI in a test tube

(c)    A sealed bottle containing Br_2 liquid and it vapours

(d)   A tree in the garden

 

10. Which of the following statements is incorrect:

(a)    Heat of reaction at constant volume is represented by \Delta E

(b)   Work done by a system is given a negative sign

(c)    Heat of reaction a constant pressure is represented by \Delta H

(d)   Endothermic compound are more stable than exothermic reaction

 

11. When 1.0 g of methane burns in oxygen 55.6 kJ of heat is produced. Enthalpy of combustion of methane is:

(a)    +889.6 kJ

(b)   -889 kJ

(c)    -55.6 kJ

(d)   +55.6 kJ

 

12. In a chemical reaction,

\Delta H = 200J and \Delta S = 20JK^{-1} at300 K

therefore at this temperature the reaction is:

(a)    Forbidden

(b)   Uncertain

(c)    Spontaneous

(d)   At equilibrium

 

13. The heat of combustion of CH_4(g) a constant volume is measured in a bomb colorimeter at 298.2 K and is found to be -885389 J / mol. The value of enthalpy change (\Delta H) is:

(a)    -890.348 kJ

(b)   -225 kJ

(c)    -450 kJ

(d)   -1560.8 kJ

 

14. In a chemical reaction \Delta G = 0 and \Delta S =20 JK^{-1} at 200 K therefore \Delta H is:

(a)    10 KJ

(b)   200 KJ

(c)    4 KJ

(d)   Zero

 

15. Which of the following process is favoured by tendency for minimum energy:

(a)    Dissociation of chlorine molecules to chlorine atoms.

(b)    The melting of ice

(c)    Dissolution of sugar

(d)   Condensation of water vapours to liquid state

 

16. For which of the following substances the enthalpy of formation in the standard state is zero?

(a)    Ethanol

(b)   Calcium chloride

(c)    Aluminum

(d)   Sucrose

 

17. In which of the following pairs do the elements have nearly the same value of bond energy?

(a)    C_2 and Br_2

(b)   F_2 and I_2

(c)    F_2 and Cl_2

(d)   I_2 and Br_2

 

18. If the door of a refrigerator is kept open, the room in which the refrigerator is kept:

(a)    neither gets cooled nor gets heated

(b)   gets heated

(c)    gets cooled

(d)   gets cooled or heated depending on the initial temperature of the room .

 

19. In a thermally isolated process:

(a)    Q = 0

(b)   \Delta C_p = 0

(c)    W = 0

(d)   \Delta H = negative

 

20. When a compressed gas is allowed to pass through a porous plug at a temperature above its inversion temperature, there is:

(a)    neither a fall nor a rise in temperature

(b)   a rise in temperature

(c)    a fall in temperature first, followed by a rise of the same

(d)   a fall in temperature

 

21. Which of the following expressions is correct?

(a)    \dfrac{\partial ln K}{\partial T} = \dfrac{E_a}{RT^2}

(b)   [\dfrac{\partial ln K_c}{\partial T}] = \dfrac{\Delta U}{RT^2}

(c)    [\dfrac{\partial ln K_p}{\partial T}] = \dfrac{\Delta H^0}{RT^2}

(d)   All of these

 

22. The standard molar enthalpy of formation of CO_2 is equal to:

(a)    the standard molar enthalpy of combustion of gaseous carbon

(b)   the sum of the standard molar enthalpies of formation of CO and O_2

(c)    zero

(d)   the standard molar enthalpy of combustion of carbon (graphite)

 

23. Which of the following expressions is correct for an equilibrium reaction?

(a)    (dS)_{U, V} \ge 0

(b)   (\partial S)_{T, P} \le 0

(c)    (\partial S)_{T, V} \le 0

(d)   All of these

 

24. Which of the following expressions is correct for an ideal gas?

(a)    (\partial A / \partial P)_T = V

(b)   (\partial C_p / \partial_p)_T = 0

(c)    (\partial S / \partial V)_T = P/T

(d)   All of these

 

25. Which of the following is correct for and adiabatic process?

(a)    Q = +w

(b)   \Delta U = q

(c)    P \Delta V = 0

(d)   q = 0

Answers:

1.(c)            2. (b)             3. (b)         4. (a)         5. (a)

6. (a)          7. (a)             8. (b)          9. (c)        10. (d)

11. (b)        12. (c)            13. (a)        14. (c)       15. (d)

16. (c)        17. (b)           18. (b)        19. (a)       20. (b)

21. (d)      22. (d)           23. (d)        24. (d)       25. (d)

 



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