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Ch.11 - Liquids, Solids & Intermolecular Forces
Tro - Chemistry: A Molecular Approach 4th Edition
Tro4th EditionChemistry: A Molecular ApproachISBN: 9780134112831당신이 사용하는 게 아니라요?교과서 변경
모든 교과서Tro 4th EditionCh.11 - Liquids, Solids & Intermolecular Forces문제 65
11장, 문제 65

Carbon disulfide has a vapor pressure of 363 torr at 25 °C and a normal boiling point of 46.3 °C. Find ΔHvap for carbon disulfide.

검증된 단계별 안내
1
Identify the Clausius-Clapeyron equation: \( \ln \left( \frac{P_2}{P_1} \right) = -\frac{\Delta H_{\text{vap}}}{R} \left( \frac{1}{T_2} - \frac{1}{T_1} \right) \), where \( P_1 \) and \( P_2 \) are the vapor pressures at temperatures \( T_1 \) and \( T_2 \), respectively, and \( R \) is the ideal gas constant.
Recognize that the normal boiling point is the temperature at which the vapor pressure equals 1 atm (760 torr). Thus, \( P_2 = 760 \text{ torr} \) and \( T_2 = 46.3 \degree C \) (convert to Kelvin by adding 273.15).
Use the given vapor pressure at 25 °C: \( P_1 = 363 \text{ torr} \) and \( T_1 = 25 \degree C \) (convert to Kelvin by adding 273.15).
Substitute the known values into the Clausius-Clapeyron equation to solve for \( \Delta H_{\text{vap}} \).
Rearrange the equation to isolate \( \Delta H_{\text{vap}} \): \( \Delta H_{\text{vap}} = -R \cdot \frac{\ln \left( \frac{P_2}{P_1} \right)}{\left( \frac{1}{T_2} - \frac{1}{T_1} \right)} \).

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주요 개념

질문에 올바르게 답하기 위해 반드시 이해해야 하는 핵심 개념들은 다음과 같습니다.

Vapor Pressure

Vapor pressure is the pressure exerted by a vapor in equilibrium with its liquid or solid phase at a given temperature. It reflects the tendency of particles to escape from the liquid phase into the vapor phase. A higher vapor pressure indicates a greater volatility of the substance, which is crucial for understanding phase changes and calculating thermodynamic properties like enthalpy of vaporization.
추천 영상:
가이드 코스
02:40
Raoult's Law and Vapor Pressure

Enthalpy of Vaporization (ΔH<sub>vap</sub>)

The enthalpy of vaporization (ΔH<sub>vap</sub>) is the amount of energy required to convert a unit quantity of a liquid into vapor at constant temperature and pressure. It is a critical parameter in thermodynamics that helps quantify the energy changes associated with phase transitions. This value can be determined using the Clausius-Clapeyron equation, which relates vapor pressure and temperature to ΔH<sub>vap</sub>.
추천 영상:
가이드 코스
01:37
Enthalpy of Vaporization Example

Clausius-Clapeyron Equation

The Clausius-Clapeyron equation describes the relationship between the vapor pressure of a substance and its temperature, allowing for the calculation of the enthalpy of vaporization. It is expressed as d(ln P)/dT = ΔH<sub>vap</sub>/(RT²), where P is the vapor pressure, T is the temperature, R is the ideal gas constant, and ΔH<sub>vap</sub> is the enthalpy of vaporization. This equation is essential for solving problems involving phase changes and thermodynamic properties.
추천 영상:
가이드 코스
00:59
Clausius-Clapeyron Equation
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