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Class XI Chemistry Thermodynamics 3: Enthalpy Change

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Question 1

One mole of magnesium in the vapour state absorbed 1200 kJ of energy. If the first and second ionization enthalpies of magnesium are 750 and 1450 kJ mol^-1 respectively, the final composition of the mixture is

Question 2

5.6 litres of an unknown gas at NTP requires 12.5 calories to raise its temperature by 10 °C at constant volume. Then atomicity of the gas is ?

Question 3

The ionization enthalpy of hydrogen atom is 1.312 × 10⁶J mol^–1. The energy required to excite the electron in the atom from n = 1 to n = 2 is

Question 4

One mole of magnesium in the vapour state absorbed 1200 kJ of energy. If the first and second ionization enthalpies of magnesium are 750 and 1450 kJ mol^–1respectively, the final composition of the mixture is

Question 5

The energy required to break one mole of Cl — Cl bonds in Cl₂ is 242 kJ mol^–1. The longest wavelength of light capable of breaking a single Cl — Cl bond is (c = 3 ×10^–8 ms^–1 and N_A = 6.02 × 10²³ mol^–1)

Question 6

The standard enthalpy of formation of NH₃ is – 46.0 kJ mol^–1. If the enthalpy of formation of H₂ from its atoms is – 436 kJ mol^–1 and that of N₂ is – 712 kJ mol^–1, the average bond enthalpy of N – H bond in NH₃ is

Question 7

The standard enthalpy of formation (Δ_fH °) at 298 K for methane, CH₄(g), is — 74.8 kJ mol^–1. The additional information required to determine the average energy for C —H bond formation would be

Question 8

The enthalpy changes for the following processes are listed below:
Cl₂(g) →2Cl (g), 242.3 kJ mol^–1
I₂(g) →2 I(g), 151.0 kJ mol^–1
ICl (g) → I(g) + Cl(g), 211.3 kJ mol^–1
I₂(s)→ I₂(g), 62.76 kJ mol^–1
Given that the standard states for iodine and chlorine are I₂(s) and Cl₂(g), the standard enthalpy of formation for ICl (g) is

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Nov 11JEE & BITSAT