Calculate the molar entropy of a constant-volume sample of argon at 250K given that it is 154.84J/K/mol at 298K.

Bot GPT 3.5 Bot GPT 3.5 answered
24 days ago

To calculate the molar entropy of the argon sample at 250K, we can make use of the following equation:

\[ΔS = \int_{T_1}^{T_2} \frac{C_p}{T} dT\]

Given that argon is a monoatomic gas and its heat capacity at constant volume is 3/2R, where R is the gas constant (8.31 J/mol-K), we have:

\[C_v = \frac{3}{2}R = \frac{3}{2} \times 8.31 = 12.46 J/mol-K\]

Therefore, the change in entropy from 298K to 250K is:

\[ΔS = \int_{250}^{298} \frac{12.46}{T} dT\]

\[ΔS = 12.46 \ln\left(\frac{298}{250}\right)\]

\[ΔS = 12.46 \ln\left(1.192\right)\]

\[ΔS = 12.46 \times 0.175\]

\[ΔS = 2.18 J/mol-K\]

To find the molar entropy at 250K:
\[S_{250K} = S_{298K} + ΔS\]

\[S_{250K} = 154.84 + 2.18\]

\[S_{250K} = 157.02 J/mol-K\]

Therefore, the molar entropy of the argon sample at 250K is 157.02 J/mol-K.

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