Tamil Nadu Board of Secondary EducationHSC Science Class 11th

# Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide chapter 7 - Thermodynamics [Latest edition]

#### Chapters ## Chapter 7: Thermodynamics

Choose the best answer [Pages 221 - 224]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide Chapter 7 ThermodynamicsChoose the best answer [Pages 221 - 224]

Choose the best answer | Q I. 1. | Page 221

The amount of heat exchanged with the surrounding at constant pressure is given by the quantity

• ∆E

• ∆H

• ∆S

• ∆G

Choose the best answer | Q I. 2. | Page 221

All the naturally occurring processes proceed spontaneously in a direction which leads to

• decrease in entropy

• increase in enthalpy

• increase in free energy

• decrease in free energy

Choose the best answer | Q I. 3. | Page 221

In an adiabatic process, which of the following is true?

• q = w

• q = 0

• ∆E = q

• P ∆ V = 0

Choose the best answer | Q I. 4. | Page 221

In a reversible process, the change in entropy of the universe is

• > 0

• ≥ 0

• < 0

• = 0

Choose the best answer | Q I. 5. | Page 221

In an adiabatic expansion of an ideal gas

• w = – ∆u

• w = ∆u + ∆H

• ∆u = 0

• w = 0

Choose the best answer | Q I. 6. | Page 221

The intensive property among the quantities below is

• mass

• volume

• enthalpy

• "mass"/"volume"

Choose the best answer | Q I. 7. | Page 221

An ideal gas expands from the volume of 1 × 10–3 m3 to 1 × 10–2 m3 at 300 K against a constant pressure at 1 × 105 Nm–2. The work done is

• – 900 J

• 900 kJ

• 270 kJ

• – 900 kJ

Choose the best answer | Q I. 8. | Page 221

Heat of combustion is always ___________.

• positive

• negative

• zero

• either positive or negative

Choose the best answer | Q I. 9. | Page 221

The heat of formation of CO and CO2 are – 26.4 kCal and – 94 kCal, respectively. Heat of combustion of carbon monoxide will be

• + 26.4 kcal

• – 67.6 kcal

• – 120.6 kcal

• + 52.8 kcal

Choose the best answer | Q I. 10. | Page 222

C(diamond) → C(graphite), ∆H = –ve, this indicates that

• graphite is more stable than diamond

• graphite has more energy than diamond

• both are equally stable

• stability cannot be predicted

Choose the best answer | Q I. 11. | Page 222

The enthalpies of the formation of Al2O3 and Cr2O3 are – 1596 kJ and – 1134 kJ, respectively. ∆H for the reaction $\ce{2Al + Cr2O3 -> 2Cr + Al2O3}$ is

• – 1365 kJ

• 2730 kJ

• – 2730 kJ

• – 462 kJ

Choose the best answer | Q I. 12. | Page 222

Which of the following is not a thermodynamic function?

• internal energy

• enthalpy

• entropy

• frictional energy

Choose the best answer | Q I. 13. | Page 222

If one mole of ammonia and one mole of hydrogen chloride are mixed in a closed container to form ammonium chloride gas, then

• ∆H > ∆U

• ∆H − ∆U = 0

• ∆H + ∆U = 0

• ∆H < ∆U

Choose the best answer | Q I. 14. | Page 222

Change in internal energy, when 4 kJ of work is done on the system and 1 kJ of heat is given out by the system is

• + 1 kJ

• – 5 kJ

• + 3 kJ

• – 3 kJ

Choose the best answer | Q I. 15. | Page 222

The work done by the liberated gas when 55.85 g of iron (molar mass 55.85 g mol–1) reacts with hydrochloric acid in an open beaker at 25°C

• – 2.48 kJ

• – 2.22 k

• + 2.22 kJ

• + 2.48 kJ

Choose the best answer | Q I. 16. | Page 222

The value of ∆H for cooling 2 moles of an ideal monatomic gas from 125°C to 25°C at constant pressure will be ["given C"_"P" = 5/2"R"]

• – 250 R

• – 500 R

• 500 R

• + 250 R

Choose the best answer | Q I. 17. | Page 222

Given that $\ce{C_{(g)} + O2_{(g)} -> CO2_{(g)}}$ ∆H° = – a kJ; $\ce{2CO_{(g)} + O2_{(g)} -> 2CO2_{(g)}}$ ∆H° = – b kJ; Calculate the ∆H° for the reaction $\ce{C_{(g)} + 1/2O2_{(g)} -> CO_{(g)}}$

• ("b" + 2"a")/2

• 2 − b

• (2"a" - "b")/2

• ("b" - 2"a")/2

Choose the best answer | Q I. 18. | Page 223

When 15.68 litres of a gas mixture of methane and propane are fully combusted at 0°C and 1 atmosphere, 32 litres of oxygen at the same temperature and pressure are consumed. The amount of heat released from this combustion in kJ is (∆HC(CH4) = – 890 kJ mol−1 and ∆HC(C3H8) = – 2220 kJ mol−1)

• – 889 kJ

• – 1390 kJ

• – 3180 kJ

• – 632.68 kJ

Choose the best answer | Q I. 19. | Page 223

The bond dissociation energy of methane and ethane are 360 kJ mol–1 and 620 kJ mol–1 respectively. Then, the bond dissociation energy of the C-C bond is

• 170 kJ mol–1

• 50 kJ mol–1

• 80 kJ mol–1

• 220 kJ mol–1

Choose the best answer | Q I. 20. | Page 223

The correct thermodynamic conditions for the spontaneous reaction at all temperature is

• ∆H < 0 and ∆S > 0

• ∆H < 0 and ∆S < 0

• ∆H > 0 and ∆S = 0

• ∆H > 0 and ∆S > 0

Choose the best answer | Q I. 21. | Page 223

The temperature of the system, decreases in an ___________.

• Isothermal expansion

• Isothermal Compression

Choose the best answer | Q I. 22. | Page 223

In an isothermal reversible compression of an ideal gas the sign of q, ∆S and w are respectively

• +, –, –

• –, +, –

• +, –, +

• –, –, +

Choose the best answer | Q I. 23. | Page 223

Molar heat of vapourisation of a liquid is 4.8 kJ mol–1. If the entropy change is 16 J mol–1 K–1, the boiling point of the liquid is

• 323 K

• 27°C

• 164 K

• 0.3 K

Choose the best answer | Q I. 24. | Page 223

∆S is expected to be maximum for the reaction

• $\ce{Ca_{(S)} + 1/2O2_{(g)} -> CaO_{(S)}}$

• $\ce{C_{(S)} + O2_{(g)} -> CO2_{(g)}}$

• $\ce{N2_{(g)} + O2_{(g)} -> 2NO_{(g)}}$

• $\ce{CaCO3_{(S)} -> CaO_{(S)} + CO2_{(g)}}$

Choose the best answer | Q I. 25. | Page 224

The values of ∆H and ∆S for a reaction are respectively 30 kJ mol–1 and 100 JK–1 mol–1. Then the temperature above which the reaction will become spontaneous is

• 300 K

• 30 K

• 100 K

• 20°C

Write brief answer to the following questions [Pages 224 - 227]

### Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide Chapter 7 ThermodynamicsWrite brief answer to the following questions [Pages 224 - 227]

Write brief answer to the following questions | Q II. 1. | Page 224

State the first law of thermodynamics.

Write brief answer to the following questions | Q II. 2. | Page 224

Define Hess's law of constant heat summation.

Write brief answer to the following questions | Q II. 3. | Page 224

Explain intensive properties with two examples.

Write brief answer to the following questions | Q II. 4. a. | Page 224

Define the following term:

Isothermal process

Write brief answer to the following questions | Q II. 4. b. | Page 224

Define the following term:

Write brief answer to the following questions | Q II. 4. c. | Page 224

Define the following term:

Isobaric process

Write brief answer to the following questions | Q II. 4. d. | Page 224

Define the following term:

Isochoric process

Write brief answer to the following questions | Q II. 5. | Page 224

What is the usual definition of entropy?

Write brief answer to the following questions | Q II. 5. | Page 224

What is the unit of entropy?

Write brief answer to the following questions | Q II. 6. i) | Page 224

Predict the feasibility of a reaction when both ΔH and ΔS positive.

Write brief answer to the following questions | Q II. 6. ii) | Page 224

Predict the feasibility of a reaction when both ΔH and ΔS negative.

Write brief answer to the following questions | Q II. 6. iii) | Page 224

Predict the feasibility of a reaction when ΔH decreases but ΔS increases.

Write brief answer to the following questions | Q II. 7. | Page 224

Define is Gibb’s free energy.

Write brief answer to the following questions | Q II. 8. | Page 224

Define enthalpy of combustion.

Write brief answer to the following questions | Q II. 9. | Page 224

Define molar heat capacity.

Write brief answer to the following questions | Q II. 9. | Page 224

Write the unit of molar heat capacity.

Write brief answer to the following questions | Q II. 10. | Page 224

Define the calorific value of food.

Write brief answer to the following questions | Q II. 10. | Page 224

What is the unit of calorific value?

Write brief answer to the following questions | Q II. 11. | Page 224

Define enthalpy of neutralization.

Write brief answer to the following questions | Q II. 12. | Page 224

What is lattice energy?

Write brief answer to the following questions | Q II. 13. | Page 224

What are state and path functions? Give two examples.

Write brief answer to the following questions | Q II. 14. | Page 224

Give Kelvin a statement of the second law of thermodynamics.

Write brief answer to the following questions | Q II. 15. | Page 224

The equilibrium constant of a reaction is 10, what will be the sign of ∆G? Will this reaction be spontaneous?

Write brief answer to the following questions | Q II. 16. | Page 224

Enthalpy of neutralization is always a constant when a strong acid is neutralized by a strong base: account for the statement.

Write brief answer to the following questions | Q II. 17. | Page 225

State the third law of thermodynamics.

Write brief answer to the following questions | Q II. 18. | Page 225

Write down the Born-Haber cycle for the formation of CaCl2

Write brief answer to the following questions | Q II. 19. | Page 225

Identify the state and path functions out of the following:

1. Enthalpy
2. Entropy
3. Heat
4. Temperature
5. Work
6. Free energy
Write brief answer to the following questions | Q II. 20. | Page 225

State the various statements of the second law of thermodynamics.

Write brief answer to the following questions | Q II. 21. | Page 225

What are spontaneous reactions?

Write brief answer to the following questions | Q II. 21. | Page 225

What are the conditions for the spontaneity of a process?

Write brief answer to the following questions | Q II. 22. | Page 225

List the characteristics of internal energy.

Write brief answer to the following questions | Q II. 23. | Page 225

Explain how heat absorbed at constant volume is measured using a bomb calorimeter with a neat diagram.

Write brief answer to the following questions | Q II. 24. | Page 225

Calculate the work involved in the expansion and compression process.

Write brief answer to the following questions | Q II. 25. | Page 225

Derive the relation between ∆H and ∆U for an ideal gas. Explain each term involved in the equation.

Write brief answer to the following questions | Q II. 26. | Page 225

Suggest and explain an indirect method to calculate lattice enthalpy of sodium chloride crystal.

Write brief answer to the following questions | Q II. 27. | Page 225

List the characteristics of Gibbs free energy.

Write brief answer to the following questions | Q II. 28. | Page 225

Calculate the work done when 2 moles of an ideal gas expands reversibly and isothermally from a volume of 500 ml to a volume of 2 L at 25°C and normal pressure.

Write brief answer to the following questions | Q II. 29. | Page 225

In a constant volume calorimeter, 3.5 g of gas with molecular weight 28 was burnt in excess oxygen at 298 K. The temperature of the calorimeter was found to increase from 298 K to 298.45 K due to the combustion process. Given that the calorimeter constant is 2.5 kJ K−1. Calculate the enthalpy of combustion of the gas in kJ mol−1.

Write brief answer to the following questions | Q II. 30. | Page 225

Calculate the entropy change in the system, and surroundings, and the total entropy change in the universe during a process in which 245 J of heat flows out of the system at 77°C to the surrounding at 33°C.

Write brief answer to the following questions | Q II. 31. | Page 225

1 mole of an ideal gas, maintained at 4.1 atm and at a certain temperature, absorbs heat 3710 J and expands to 2 litres. Calculate the entropy change in the expansion process.

Write brief answer to the following questions | Q II. 32. | Page 225

30.4 kJ is required to melt one mole of sodium chloride. The entropy change during melting is 28.4 JK−1 mol−1. Calculate the melting point of sodium chloride.

Write brief answer to the following questions | Q II. 33. | Page 225

Calculate the standard heat of formation of propane, if its heat of combustion is −2220.2 kJ mol−1 the heats of formation of $\ce{CO2_{(g)}}$ and $\ce{H2O_{(l)}}$ are −393.5 and −285.8 kJ mol−1 respectively.

Write brief answer to the following questions | Q II. 34. 1. | Page 226

You are given normal boiling points and standard enthalpies of vapourisation. Calculate the entropy of vapourisation of liquids listed below.

 Liquid Boiling points (°C) ΔH (kJ mol−1) Ethanol 78.4 + 42.4
Write brief answer to the following questions | Q II. 34. 2. | Page 226

You are given normal boiling points and standard enthalpies of vapourisation. Calculate the entropy of vapourisation of liquids listed below.

 Liquid Boiling points (°C) ΔH (kJ mol−1) Toluene 110.6 + 35.2
Write brief answer to the following questions | Q II. 35. | Page 226

For the reaction $\ce{Ag2O_{(s)} -> 2Ag_{(s)} + 1/2O2_{(g)}}$: ΔH = 30.56 kJ mol−1 and ΔS = 6.66 JK−1 mol−1 (at 1 atm). Calculate the temperature at which ΔG is equal to zero. Also predict the direction of the reaction

1. at this temperature and
2. below this temperature.
Write brief answer to the following questions | Q II. 36. | Page 226

What is the equilibrium constant Keq for the following reaction at 400 K?

$\ce{2NOCl_{(g)} ⇌ 2NO_{(g)} + Cl2_{(g)}}$, given that H0 = 77.2 kJ mol−1 and ∆S0 = 122 JK1 mol1

Write brief answer to the following questions | Q II. 37. | Page 226

Cyanamide (NH2CN) is completely burnt in excess oxygen in a bomb calorimeter, ΔU was found to be −742.4 kJ mol−1, calculate the enthalpy change of the reaction at 298 K.$\ce{NH2CN_{(s)} + 3/2 O2_{(g)} -> N2_{(g)} + CO2_{(g)} + H2O_{(l)}}$ ΔH = ?

Write brief answer to the following questions | Q II. 38. | Page 226

Calculate the enthalpy of hydrogenation of ethylene from the following data.

Bond energies of C − H, C − C, C = C and H − H are 414, 347, 618 and 435 kJ mol−1.

Write brief answer to the following questions | Q II. 39. | Page 226

Calculate the lattice energy of CaCl2 from the given data

$\ce{Ca_{(s)} + Cl2_{(g)} -> CaCl2_{(s)}}$ ∆"H"_"f"^0 = − 795 kJ mol−1

Sublimation: $\ce{Ca_{(s)} -> Ca-{(g)}}$ ∆"H"_1^0 = + 121 kJ mol−1

Ionisation: $\ce{Ca_{(g)} -> Ca^2+_{(g)} + 2e^-}$ ∆"H"_2^0 = + 2422 kJ mol−1

Dissociation: $\ce{Cl2_{(g)} -> 2Cl_{(g)}}$ ∆"H"_3^0 = + 242.8 kJ mol−1

Electron affinity: $\ce{Cl_{(g)} + e^- -> Cl^-_{(g)}}$ ∆"H"_4^0 = −355 kJ mol−1

Write brief answer to the following questions | Q II. 40. | Page 226

Calculate the enthalpy change for the reaction $\ce{Fe2O3 + 3CO -> 2Fe + 3CO2}$ from the following data.

$\ce{2Fe + 3/2O2 -> Fe2O3}$; ΔH = −741 kJ

$\ce{C + 1/2O2 -> CO}$; ΔH = −137 kJ

$\ce{C + O2-> CO2}$; ΔH = −394.5 kJ

Write brief answer to the following questions | Q II. 41. | Page 227

When 1-pentyne (A) is treated with 4N alcoholic KOH at 175°C, it is converted slowly into an equilibrium mixture of 1.3% 1-pentyne (A), 95.2% 2-pentyne (B) and 3.5% of 1, 2 pentadiene (C) the equilibrium was maintained at 175°C, calculate ΔG0 for the following equilibria.

$\ce{B ⇌ A}$ Δ"G"_1^0 = ?

$\ce{B ⇌ C}$ Δ"G"_2^0 = ?

Write brief answer to the following questions | Q II. 42. | Page 227

At 33K, N2O4 is fifty percent dissociated. Calculate the standard free energy change at this temperature and at one atmosphere.

Write brief answer to the following questions | Q II. 43. | Page 227

The standard enthalpies of formation of SO2 and SO3 are −297 kJ mol−1 and −396 kJ mol−1 respectively. Calculate the standard enthalpy of reaction for the reaction: $\ce{SO2 + 1/2O2 -> SO3}$

Write brief answer to the following questions | Q II. 44. | Page 227

For the reaction at 298 K: $\ce{2A + B -> C}$

ΔH = 400 KJ mol−1; ΔS = 0.2 KJ K−1 mol−1 Determine the temperature at which the reaction would be spontaneous.

Write brief answer to the following questions | Q II. 45. | Page 227

Find out the value of the equilibrium constant for the following reaction at 298 K, $\ce{2NH3_{(g)} + CO2_{(g)} ⇌ NH2CONH2_{(aq)} + H2O_{(l)}}$ Standard Gibbs energy change, ∆"G"_"r"^0 at the given temperature is –13.6 kJ mol−1.

Write brief answer to the following questions | Q II. 46. | Page 227

A gas mixture of 3.67 lit of ethylene and methane on complete combustion at 25°C and at 1 atm pressure produce 6.11 lit of carbon dioxide. Find out the amount of heat evolved in kJ, during this combustion. (ΔHC(CH4)) = − 890 kJ mol−1 and (ΔHC(C2H4)) = − 1423 kJ mol−1

## Chapter 7: Thermodynamics ## Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide chapter 7 - Thermodynamics

Tamil Nadu Board Samacheer Kalvi solutions for Class 11th Chemistry Volume 1 and 2 Answers Guide chapter 7 (Thermodynamics) include all questions with solution and detail explanation. This will clear students doubts about any question and improve application skills while preparing for board exams. The detailed, step-by-step solutions will help you understand the concepts better and clear your confusions, if any. Shaalaa.com has the Tamil Nadu Board of Secondary Education Class 11th Chemistry Volume 1 and 2 Answers Guide solutions in a manner that help students grasp basic concepts better and faster.

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Concepts covered in Class 11th Chemistry Volume 1 and 2 Answers Guide chapter 7 Thermodynamics are Thermodynamics, System and Surrounding, Thermochemical Equations, Zeroth Law of Thermodynamics, First Law of Thermodynamics, Enthalpy (H), Measurement of ΔU and ΔH Using Calorimetry, Hess’s Law of Constant Heat Summation, Lattice Energy, Various Statements of the Second Law of Thermodynamics, Second Law of Thermodynamics, Gibbs Free Energy (G), Third Law of Thermodynamics.

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