Class 11 Chemistry - Chapter Thermodynamics NCERT Solutions | For an isolated system, ΔU = 0, wh

In a process, 701 J of heat is absorbed by a system and 394 J ofwork is done by the system. What is the change in internal energy for the process?

For the reaction, 2Cl_(g) → Cl_2(g),what are the signs of ΔH and ΔS ?

For the reaction at 298 K,

2A + B → C

ΔH = 400 kJ mol^-1and ΔS = 0.2 kJ K^-1mol^-1

At what temperature will the reaction become spontaneous considering ΔH and ΔS to be constant over the temperature range?

A reaction, A + B → C + D + q is found to have a positive entropy change. The reaction will be

(i) possible at high temperature

(ii) possible only at low temperature

(iii) not possible at any temperature

(iv) possible at any temperature

The equilibrium constant for a reaction is 10. What will be the value of ΔG⁰ ?  R = 8.314 JK^–1 mol^–1, T = 300 K.

The enthalpy of combustion of methane, graphite and dihydrogen at 298 K are, –890.3 kJ mol^–1  , –393.5 kJ mol^–1, and –285.8 kJ mol^–1 respectively. Enthalpy of formation of CH₄(g) will be

(i) –74.8 kJ mol^–1

(ii) –52.27 kJ mol^–1

(iii) +74.8 kJ mol^–1

(iv) +52.26 kJ mol^–1

Calculate the enthalpy change on freezing of 1.0 mol of water at 10.0°C to ice at -10.0°C. Δ_fusH = 6.03 kJ mol^-1 at 0°C.

C_p[H₂O(l)] = 75.3 J mol^-1 K^-1

C_p[H₂O(s)] = 36.8 J mol^-1 K^-1

Calculate the enthalpy change for the process

CCl₄(g) → C(g) + 4 Cl(g)

and calculate bond enthalpy of C – Cl in CCl₄(g).

Δ_vapH⁰(CCl₄) = 30.5 kJ mol^–1.

Δ_fH⁰ (CCl₄) = –135.5 kJ mol^–1.

Δ_aH⁰ (C) = 715.0 kJ mol^–1 , where Δ_aH⁰ is enthalpy of atomisation

Δ_aH⁰ (Cl₂) = 242 kJ mol^–1

Choose the correct answer. A thermodynamic state function is a quantity
(i) used to determine heat changes
(ii) whose value is independent of path
(iii) used to determine pressure volume work
(iv) whose value depends on temperature only.

Enthalpies of formation of CO(g), CO₂(g), N₂O(g) and N₂O₄(g) are –110, – 393, 81 and 9.7 kJ mol–1 respectively. Find the value of Δ_rH for the reaction:

N₂O₄(g) + 3CO(g) → N₂O(g) + 3CO₂(g)

How do you account for the formation of ethane during chlorination of methane?

What are hybridisation states of each carbon atom in the following compounds ?

(i) CH₂=C=O,

(ii) CH₃CH=CH₂,

(iii) (CH₃)₂CO,

(iv) CH₂=CHCN,

(v) C₆H₆

What will be the minimum pressure required to compress 500 dm³ of air at 1 bar to 200 dm³ at 30°C?

What are the common physical and chemical features of alkali metals?

Calculate the molecular mass of the following:
(i) H₂O
(ii) CO₂
(iii) CH₄

Assign oxidation number to the underlined elements in each of the following species:

(a) NaH₂PO₄

(b) NaHSO₄

(c) H₄P₂O₇

(d) K₂MnO₄

(e) CaO₂

(f) NaBH₄

(g) H₂S₂O₇

(h) KAl(SO₄)₂.12 H₂O

What is the basic theme of organisation in the periodic table?

Explain the formation of a chemical bond.

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.
a) What is the initial effect of the change on vapour pressure?
b) How do rates of evaporation and condensation change initially?
c) What happens when equilibrium is restored finally and what will be the final vapour pressure?

Justify the position of hydrogen in the periodic table on the basis of its electronic configuration.

Write IUPAC names of the products obtained by the ozonolysis of the following compounds:

(i) Pent-2-ene

(ii) 3,4-Dimethyl-hept-3-ene

(iii) 2-Ethylbut-1-ene

(iv) 1-Phenylbut-1-ene

Write the names of isotopes of hydrogen. What is the mass ratio of these isotopes?

Write bond line formulas for : Isopropyl alcohol, 2,3-Dimethyl butanal, Heptan-4- one.

What is the total number of sigma and pi bonds in the following molecules?

(a) C₂H₂ (b) C₂H₄

What are the necessary conditions for any system to be aromatic?

The value of Kc for the reaction

3O₂ (g) ↔ 2O₃ (g) is 2.0 ×10^–50 at 25°C.

If the equilibrium concentration of O² in air at 25°C is 1.6 ×10^–2, what is the concentration of O³?

Which of the following carbocation is most stable ?

Predict which of the following reaction will have appreciable concentration of reactants and products:

a) Cl₂ (g)  ↔  2Cl (g)                             Kc = 5 ×10^–39

b) Cl₂ (g) + 2NO (g)  ↔  2NOCl (g)         Kc = 3.7 × 10⁸

c) Cl₂ (g) + 2NO₂ (g)  ↔  2NO₂Cl (g)      Kc = 1.8

Arrange the following

(i) CaH₂, BeH₂ and TiH₂ in order of increasing electrical conductance.

(ii) LiH, NaH and CsH in order of increasing ionic character.

(iii) H-H, D-D and F-F in order of increasing bond dissociation enthalpy.

(iv) NaH, MgH₂ and H₂O in order of increasing reducing property.

Draw the resonance structures for the following compounds. Show the electron shift using curved-arrow notation.

(a) C₆H₅OH

(b) C₆H₅NO₂

(c) CH₃CH=CHCHO

(d) C₆H₅–CHO

(e) C₆ H₅ - C⁺H₂ 

(f)  CH₃CH = CHC⁺H₂