HSC Science इयत्ता ११ - Tamil Nadu Board of Secondary Education Question Bank Solutions for Chemistry

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

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

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 = ?

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.

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.

Define is Gibb’s free energy.

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

What are the conditions for the spontaneity of a process?

List the characteristics of Gibbs free energy.

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.

What is the equilibrium constant K_eq 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 JK⁻¹ mol⁻¹

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` = ?

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

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.

State the third law of thermodynamics.