Ncert Solutions Chemistry Class 11th

Use the following data to calculate ∆_lattice Hᶱ for NaBr. ∆_sub Hᶱ for sodium metal = 108.4 kJ/ mol

Ionization enthalpy of sodium = 496 kJ/mol

Electron gain enthalpy of bromine = – 325 kJ mol–1 Bond dissociation enthalpy of bromine = 192 kJ mol–1 ∆_f Hᶱ for NaBr (s) = – 360.1 kJ/ mol

The enthalpy of atomisation for the reaction CH₄(g)→ C(g) + 4H(g) is 1665 kJ/ mol. What is the bond energy of C–H bond?

Enthalpy is an extensive property. In general, if enthalpy of an overall reaction A→B along one route is ∆r H and ∆r H₁, ∆rH₂, ∆rH₃ . represent enthalpies of intermediate reactions leading to product B. What will be the relation between ∆r H for overall reaction and ∆rH₁ , ∆rH₂ . etc. for intermediate reactions.

The value of ∆_fHᶱ for NH₃ is – 91.8 kJ/ mol. Calculate enthalpy change for the following reaction :

2NH₃(g) → N₂(g) + 3H₂(g)

Standard molar enthalpy of formation, ∆_fHᶱ is just a special case of enthalpy of reaction, ∆r HV . Is the ∆r HV for the following reaction same as ∆f HV ? Give reason for your answer.

CaO(s) + CO₂(g) → CaCO₃(s); ∆_fHᶱ = –178.3 kJ /mol

One mole of acetone requires less heat to vapourise than 1 mol of water. Which of the two liquids has higher enthalpy of vapourisation?

18.0 g of water completely vapourises at 100°C and 1 bar pressure and the enthalpy change in the process is 40.79 kJ/ mol. What will be the enthalpy change for vapourising two moles of water under the same conditions? What is the standard enthalphy of vapourisation for water?

Graphically show the total work done in an expansion when the state of an ideal gas is changed reversibly and isothermally from (Pi, Vi) to (Pf, Vf) . With the help of a pV plot compare the work done in the above case with that carried out against a constant external pressure Pf.

ΔG is net energy available to do useful work and is thus a measure of “free energy”. Show mathematically that ΔG is a measure of free energy. Find the unit of ΔG. If a reaction has positive enthalpy change and positive entropy change, under what condition will the reaction be spontaneous?

Extensive properties depend on the quantity of matter but intensive properties do not. Explain whether the following properties are extensive or intensive. Mass, internal energy, pressure, heat capacity, molar heat capacity, density, mole fraction, specific heat, temperature and molarity.