EASY
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The latent heat of melting of ice at 0°C is 6 kJ mol-1 . The entropy change during the melting in J K-1 mol-1 is closets to-

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Important Questions on Thermodynamics

HARD
One mole of an ideal gas at 300 K in thermal contact with its surroundings expands isothermally from 1.0 L to 2.0 L against a constant pressure of 3.0 atm. In this process, the change in entropy of the surroundings Ssurr in J K-1 is:

1 L atm = 101.3 J
HARD
The entropy change associated with the conversion of 1 kg of ice at 273 K to water vapours at 383 K is:

(Specific heat of water liquid and water vapour are 4.2 kJ K- and 2.0 kJ K-1kg-1 ; heat of liquid fusion and vaporization of water are 334 kJ kg-1 and 2491 kJ kg-1 , respectively). ( log 273=2.436,log373=2.572,log383=2.583 )
MEDIUM
Calculate the entropy change in melting 1 mole of ice at 273 K ΔHf°=6.025 kJ mol-1.
MEDIUM

For the following reaction

Fe2O3s+3COg2Fes+3CO2g ΔH°=-29.8 kJ and ΔS°=15 JK-1. What is the value of ΔStotal at 298 K?

EASY
When the same quantity of heat is absorbed by a system at two different temperatures T1 and T2, such that T1>T2, change in entropies are ΔS1 and ΔS2 respectively. Then:
EASY
For the reaction, 2ClgCl2g, the correct option is
EASY
The entropy of a perfectly crystalline solid at absolute zero temperature is:
MEDIUM
For the process H2O lH2Og  at T=100oC  and 1 atmosphere pressure, the correct choice is-
HARD

A container is divided into two compartments by a removable partition as shown below:

Question Image

In the first compartment, n1 moles of ideal gas He is present in a volume V1. In the second compartment, n2 moles of ideal gas Ne is present in a volume V2. The temperature and pressure in both the compartments are T and P, respectively. Assuming R is the gas constant, the total change in entropy upon removing the partition when the gases mix irreversibly is:

MEDIUM
For which of the following processes, S is negative?
MEDIUM

Which of the following show an increase in entropy?

I. Boiling of water

II. Melting of ice

III. Freezing of water

IV. Formation of hydrogen gas from water

MEDIUM

During which of the following processes, does entropy decrease ?

(A) Freezing of water to ice at 0°C
(B) Freezing of water to ice at -10°C
(C) N2( g)+3H2( g)2NH3( g)
(D) Adsorption of CO(g) and lead surface
(E) Dissolution of NaCl in water

MEDIUM
What will be the entropy change of the system when expansion of 1 mole of a gas takes place from 3 L to 6 L under isothermal conditions? Consider R=2cal K-1 mole-1 and log2=0.301.
EASY
The volume of one mole of an ideal gas is increased to 10 times of its initial volume isothermally and reversibly. The change in entropy is
MEDIUM
The entropy change in the isothermal reversible expansion of 2 moles of an ideal gas from 10 to 100 at 300 K is
EASY
For a sample of perfect gas, when its pressure is changed isothermally from pi to pf, the entropy change is given by