The temperature of n moles of a gas is increased from T_i to T_f at constant pressure.If the molar specific heat at constant pressure is C_p and is independent of temperature, then change in the entropy of the gas is: A)nC_p ln(T_f/T_i) B)nC_p ln(T_i/T_f) C)nC_p ln(T_f - T_i) D)nC_p ln(1 - T_i/T_f) E)nC_p (T_f - T_i)

Question

Quizplus · Accepted Answer

The change in entropy can be calculated using the formula ΔS = nCp ln(Tf/Ti) where n is the number of moles of gas, Cp is the molar specific heat at constant pressure, Tf and Ti are the final and initial temperatures respectively. Since Cp is independent of temperature, it can be taken outside the logarithm. Thus, the final expression becomes ΔS = nCp ln(Tf/Ti). This matches with option A.

The Temperature of N Moles of a Gas Is Increased