Class 11 Chemistry - Chapter Thermodynamics NCERT Solutions | The enthalpy of combustion of methane, g

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.

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

For an isolated system, ΔU = 0, what will be ΔS?

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.

Calculate the molarity of a solution of ethanol in water in which the mole fraction of ethanol is 0.040 (assume the density of water to be one).

If 0.561 g of KOH is dissolved in water to give 200 mL of solution at 298 K. Calculate the concentrations of potassium, hydrogen and hydroxyl ions. What is its pH?

Although geometries of NH₃ and H₂O molecules are distorted tetrahedral, bond angle in water is less than that of ammonia. Discuss.

What would have happened if the greenhouse gases were totally missing in the earth's atmosphere? Discuss.

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:

CH₃COOH (l) + C₂H₅OH (l) ↔ CH₃COOC₂H₅ (l) + H₂O (l)

(i) Write the concentration ratio (reaction quotient), Q_c, for this reaction (note: water is not in excess and is not a solvent in this reaction)

(ii) At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant.

(iii) Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after sometime. Has equilibrium been reached?

Write IUPAC names of the following compounds :

At a certain temperature and total pressure of 10⁵ Pa, iodine vapour contains 40% by volume of I atoms

I_2(g)    ↔    2l _(g)

Calculate K_p for the equilibrium.

Comment on each of the following observations:

(a) The mobilities of the alkali metal ions in aqueous solution are Li⁺ <  Na⁺ <  K⁺ <  Rb⁺ < Cs⁺

(b) Lithium is the only alkali metal to form a nitride directly.

(c) E° for M²⁺(aq) (where M = Ca, Sr or Ba) is nearly constant.

How can saline hydrides remove traces of water from organic compounds?

Write the general outer electronic configuration of s-, p-, d- and f- block elements.