CHEMICAL THERMODYNAMICS

Which of the following property cannot be used to describe state of a system?

• Pressure

• Volume

• Temperature

• Universal Gas Constant

The system that does not allow the heat to pass through its boundary between the system and surrounding is called as............ System.

• Adiabatic

• Open

• Isothermal

• Closed

An open system allows the transfer of

• Only mass

• Only Energy

• Both mass and energy

• Neither mass nor energy

One mole of which of the following has the highest entropy?

• Liquid nitrogen

• Hydrogen gas

• Mercury

• Diamond

The Enthalpy of vaporisation of a substance is 8400J/mol and it's boiling pt. is -173°C.The entropy change for vaporisation is:

• 84J/mol/K

• 21J/mol/K

• 49J/K/mol

• 12 J/K/mol

A system absorb 10kJ of heat at constant volume and it's temp. rises from 270°C to 370°C.The value of ∆U is

• 100 kJ

• 10kJ

• 0 kJ

• 1 kJ

In which of the following process a maximum increase in entropy is observed?

• Dissolution of salt in water

• Condensation of water

• Sublimation of naphthalene

• Melting of ice

Based on the 1st law of thermodynamics, which one of the following is correct?

• For an isothermal process, q=+w

• For an isochoric process ∆U=-q

• For an adiabatic process, ∆U= -W

• For cyclic process, q= -W

For the reaction C(s)+O2(g)→CO2(g)

• ∆H>∆U

• ∆H<∆U

• ∆H=∆U

• None of these

Answer explanation

Because ∆ng=0

For an ideal gas, Cv and Cp are related as:

• Cv-Cp = R

• Cv+Cp=R

• Cp-Cv=RT

• Cp-Cv=R