Carbon disulfide 1CS22 is a toxic, highly flammable substance. The following thermodynamic data are available for CS21l2 and CS21g2 at 298 K: (e) Use the data in the table to calculate ΔS° at 298 K for the vaporization of CS21l2. Is the sign of ΔS° as you would expect for a vaporization?

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Identify the standard entropy values (S°) for both the liquid and gaseous states of CS2 from the provided table.

Calculate the change in entropy (ΔS°) for the vaporization process using the formula: ΔS° = S°(g) - S°(l), where S°(g) is the entropy of CS2 in the gaseous state and S°(l) is the entropy of CS2 in the liquid state.

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Analyze the sign of ΔS°. For vaporization, the entropy typically increases as the substance changes from a more ordered liquid state to a less ordered gaseous state.

Expect a positive ΔS° value, indicating an increase in disorder and entropy as CS2 transitions from liquid to gas.

Compare your calculated ΔS° with typical entropy changes for vaporization to verify if the result is within a reasonable range.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Thermodynamics of Phase Changes

Thermodynamics studies the relationships between heat, work, and energy. In the context of phase changes, such as vaporization, it examines how energy is absorbed or released when a substance transitions from one phase to another. For vaporization, energy is required to overcome intermolecular forces, leading to an increase in entropy as the liquid transforms into a gas.

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Entropy in Phase Changes

Entropy (ΔS°)

Entropy is a measure of the disorder or randomness in a system. The change in entropy (ΔS°) during a process indicates how much the disorder changes. For vaporization, the transition from a liquid to a gas results in a significant increase in disorder, as gas molecules are more spread out and move freely compared to liquid molecules, typically resulting in a positive ΔS°.

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Entropy in Thermodynamics

Standard State Conditions

Standard state conditions refer to a set of specific conditions (usually 1 atm pressure and a specified temperature, often 298 K) under which thermodynamic data is measured. This standardization allows for consistent comparisons of thermodynamic properties, such as enthalpy and entropy, across different substances and reactions, facilitating calculations like ΔS° for processes such as vaporization.

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Standard Reduction Potentials

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