Concept explainers
Phosphorus exists as several allotropes that have varying properties. The enthalpy of transition from white P to red P,
Interpretation:
The temperature at which the white phosphorus becomes the stable phase at
Concept introduction:
The clausius-clapeyron equation states the relation between vapor pressure and the absolute temperature.
The alternate form of Clausius-Clapeyron equation is,
Answer to Problem 6.25E
The temperature at which the white phosphorus become the stable phase at
Explanation of Solution
Given
The density of white phosphorus is
The density of red phosphorus is
Molar mass of phosphorus is
The enthalpy of transition from white P to red P,
The alternate form of Clausius-Clapeyron equation is,
The final temperature is calculated by the equation,
First, the molar volumes of each phosphorus atom are calculated with the help of their densities. The molar volumes are calculated by the formula,
Substitute the values of molar mass and density of white phosphorus,
Similarly, the molar volume of red phosphorus is calculated as,
The initial temperature,
The conversion of Celsius to Kelvin is done as,
Therefore, the conversion of
The initial pressure,
The final pressure is
Substitute the values of the enthalpy of transition, change in molar volume, pressure and initial temperature in equation (2) to calculate the final temperature.
Simplify the above expression,
Hence, the temperature at which the white phosphorus become the stable phase at
The temperature at which the white phosphorus become the stable phase at
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Chapter 6 Solutions
Physical Chemistry
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