MEDIUM
11th CBSE
IMPORTANT
Earn 100

H and S for the vaporization of water at 1 atm pressure are 40.63 kJ mol-1 and 108.8 J K-1 mol-1 respectively. Calculate the temperature at which the free energy for this transformation will be zero. Predict, giving reasons, the sign of free energy change (G) above this temperature.

Important Questions on Thermodynamics

MEDIUM
11th CBSE
IMPORTANT

In the reaction A++BA+B+, there is no entropy change. Enthalpy change, H, equals 22 kJ mol-1 of A+. Calculate G for the reaction. Under what condition free energy change will have negative value?

EASY
11th CBSE
IMPORTANT
Calculate the free energy change in dissolving one mole of sodium chloride at 25°C. Lattice energy=+777.8 kJ mol-1. Hydration energy of NaCl=-774.1 kJ mol-1 and S at 25°C=0.043 kJ K-1 mol-1.
MEDIUM
11th CBSE
IMPORTANT
The following data is known about the melting of KCl: H= 7.25 kJ mol-1 and S= 0.007 kJ K-1 mol-1. Calculate the melting point.
HARD
11th CBSE
IMPORTANT

The free energy changes for the two reactions given below are:

SO2(g)+Cl2(g)SO2Cl2(g), G=-2270 cal.

S(rhom)+O2(g)+Cl2(g)SO2Cl2(g), G=-74060 cal.

Find G for the reaction: S(rhom)+O2(g)SO2(g).

HARD
11th CBSE
IMPORTANT

At what temperature, reduction of lead oxide to lead by carbon, i.e., PbO(s)+C(s)Pb(s)+CO(g) becomes spontaneous. For the reaction, H and S are 108.4 kJ mol-1 and 190.0 J K-1 mol-1 respectively.

HARD
11th CBSE
IMPORTANT
For the reaction: 2NO(g)+O2(g)2NO2(g), the enthalpy and entropy changes are -113·0 kJ mol-1 and -145 J K-1 mol-1 respectively. Find the temperature below which this reaction is spontaneous.
HARD
11th CBSE
IMPORTANT
For a hypothetical reaction, XY, the enthalpy and entropy changes are 46.3 kJ mol-1 and 108.80 J K-1 mol-1 respectively. Find the temperature above which this reaction is spontaneous.
MEDIUM
11th CBSE
IMPORTANT
The standard free energy change for a reaction is - 212.3 kJ mol-1. If the enthalpy change of the reaction is- 216.7 kJ mol-1, calculate the entropy change for the reaction. T=25 °C=298 K.