Chapter 10: clapeyron equation
Maxwell Relations are from great importance for thermodynamics because they help to determine the enthalpy changes that are impossible to measure. Clapeyron equation comes from the next Maxwell Relation.
During a phase change, the pressure is the same as the saturation pressure so it depends only of the temperature.
In an isothermal process in a liquid-vapor phase change, the integral of the Maxwell Relation gives the next equation.
The pressure remains constant through all the process.
Substituting equation (5) in equation (4), we get Clapeyron equation.
Clapeyron equation determine the enthalpy of vaporization at any given temperature. It is useful at any phase change process with pressure and temperature remaining constant. At low pressures, vapor can be considered as an ideal gas.
Substituting equation (7) in equation (6).
The integral from equation (9), we get Clausius-Clapeyron equation.
Applications
The Clapeyron Equation can be used to analyze the relationships between vapor pressure, temperature, and enthalpy of vaporization. In a study for the American Journal of Physics, the equation was used in conjunction with vapor pressure curves to analyze the composition and density of atmospheric clouds on different planets.
Reference: Sánchez-Lavega, Agustı́n, Santiago Perez-Hoyos, and Ricardo Hueso. "Clouds in Planetary Atmospheres: A Useful Application of the Clausius–Clapeyron Equation." American Journal of Physics (n.d.): n. pag. American Association of Physics Teachers. Web. 26 Oct. 2016.
Reference: Sánchez-Lavega, Agustı́n, Santiago Perez-Hoyos, and Ricardo Hueso. "Clouds in Planetary Atmospheres: A Useful Application of the Clausius–Clapeyron Equation." American Journal of Physics (n.d.): n. pag. American Association of Physics Teachers. Web. 26 Oct. 2016.
Reference
Jaramillo. O. (25 de abril de 2007) Notas de Físico-Química. UNAM. Recuperado de http://www.cie.unam.mx/~ojs/pub/Liquid3/liquid3pdf.pdf Polilibros (15 abril del 2009) Problemario termodinámica y fisicoquímica , IPN Recuperado de: http://servicios.encb.ipn.mx/polilibros/fisicoquimica/PRESION%20DE%20VAPOR/problemas.htm |
EXAMPLE
ANOTHER EXERCISE TO PRACTICE
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