The expression for entropy change, ΔS = nCp.ln$$\left( {\frac{{{{\text{T}}_2}}}{{{{\text{T}}_1}}}} \right),$$ is valid for the __________ of a substance.
A. Simultaneous pressure & temperature change
B. Heating
C. Cooling
D. Both B and C
Answer: Option D
Solution(By Examveda Team)
Actually the Entropy of an ideal gas is given by:$$\Delta S = \int_{{T_i}}^{{T_f}} {} \frac{{{C_p}dT}}{T} - nR\ln \left( {\frac{{{P_f}}}{{{P_i}}}} \right).$$
$$ \Rightarrow $$ it depends upon both temperature and pressure.
Under constant pressure process we can write $$\Delta S = {C_p}.\ln \left( {\frac{{{T_f}}}{{{T_i}}}} \right).$$ The final temperature can be greater or lesser than the initial temperature.
Related Questions on Chemical Engineering Thermodynamics
A. Maxwell's equation
B. Thermodynamic equation of state
C. Equation of state
D. Redlich-Kwong equation of state
Henry's law is closely obeyed by a gas, when its __________ is extremely high.
A. Pressure
B. Solubility
C. Temperature
D. None of these
A. Enthalpy
B. Volume
C. Both A & B
D. Neither A nor B
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