ClausiusClapeyron Equation 
Calculator & Plotter
Chemistry Software Download
Introduction and Theory
The ClausiusClapeyron equation is a
fundamental relation in thermodynamics that describes the phase
transition between two phases of a substance, specifically
vaporization and condensation. It relates the pressure and
temperature of a system undergoing a phase change, allowing us to
understand how vapor pressure changes with temperature for a given
substance.
ClausiusClapeyron Equation
The ClausiusClapeyron equation is typically expressed in its
logarithmic form:
$\ln\left(\frac{P_1}{P_2}\right)
= \frac{\Delta H_{\text{vap}}}{R}\left(\frac{1}{T_2} 
\frac{1}{T_1}\right)$
Where:
 $P_1$and
${P}_{2}$
are the vapor pressures in Pa, atm or mmHg at two different
temperatures ${T}_{1}$and
${T}_{2}$
given in Celsius , Fahrenheit or Kelvin,
 $\mathrm{\Delta}{H}_{\text{vap}}$
is the enthalpy (heat) of vaporization (J/mol),
 $R$ is
the universal gas constant ($R=8.314\text{\hspace{0.17em}}\text{J/(mol*}{\text{}}\text{K)}$).
This equation enables the calculation of vapor pressure at a
temperature $T_2$,
given a known vapor pressure at temperature $T_1$
and the enthalpy of vaporization for the compound. The equation is
particularly useful for predicting the behavior of substances
undergoing phase transitions, such as from liquid to vapor, and is
foundational in understanding boiling points, sublimation, and
condensation in a wide range of scientific applications.
Theoretical Significance
The ClausiusClapeyron equation is essential in physical
chemistry and engineering applications, especially for systems
involving heat engines, refrigeration cycles, meteorology, and
chemical reactions. It allows the prediction of how substances
behave under various pressure and temperature conditions.
The equation assumes that the enthalpy of vaporization remains
constant over the temperature range and that the vapor behaves
ideally (follows the ideal gas law). Although these assumptions
may introduce small errors at high pressures or very low
temperatures, the equation is widely used due to its simplicity
and reasonable accuracy.
ClausiusClapeyron Equation  Calculator and
Plotter Description
The ClausiusClapeyron calculator and plotter offers a practical
way to explore the relationship between temperature and vapor
pressure. With an intuitive user interface, the tool enables the
user to calculate vapor pressures and visualize these
relationships for different compounds, making it a valuable
resource in thermodynamics and physical chemistry. The ability to
export data for further analysis ensures that this tool can be
integrated into more complex workflows. The Plotter
is a powerful feature of the calculator that graphically displays
the relationship between vapor pressure $P_2$
(on the yaxis) and temperature $T_2$
(on the xaxis).
The ClausiusClapeyron Calculator is an
intuitive tool designed to perform calculations and generate plots
based on the ClausiusClapeyron equation. The calculator includes
several key components and options for user interaction:
Main Components of the Calculator

Text Fields: The calculator has six text
fields:
 P1: The reference vapor pressure at
temperature ${T}_{1}$
(greyed out).
 T1: The reference temperature (greyed
out).
 P2: The vapor pressure at the
userspecified temperature ${T}_{2}$.
 T2: The temperature at which the vapor
pressure is calculated.
 $\Delta
H_{\text{vap}}$:
The enthalpy of vaporization (greyed out).
 R: The universal gas constant (greyed
out).

Editable Fields: Only P2
and T2 are usereditable, meaning the user
can input these values for calculations.

Dropdown Lists:
 Behind the P2 field, a dropdown list
allows the selection of pressure units: Pa,
atm, or mmHg.
 Behind the T2 field, the user can select
the temperature units: Kelvin (K), Celsius
(°C), or Fahrenheit (°F).
 The Compound dropdown list is located next to the
copy to clipboard button.
Constants and Variables
 R: The universal gas constant, $R = 8.314 \,
\text{J/mol·K}$, is fixed and
used in the equation.
 $\mathrm{\Delta}{H}_{\text{vap}}$:
The enthalpy of vaporization, typically a known constant for
each compound (in J/mol).
 P1: The known vapor pressure at the boiling
point temperature T1 (1atm).
 T1: The boiling point temperature at 1atm.
Fig. CHEMIX School Gas Equations:
Boilingpoint of Water at 1atm (100°C) and boilingpoint at
0.08atm (40°C)
Fig. Propane, Water and Glycerol
Boiling point curves pasted into CHEMIX School 
Binary Plot
Features of the Plotter:

Compound Selection:
 Users can select a specific compound from a dropdown
list. The selected compound determines the value of $\mathrm{\Delta}{H}_{\text{vap}}$,
${P}_{1}$
, and ${T}_{1}$,
based on known thermodynamic properties.

Graphical Representation:
 The graph plots vapor pressure on the yaxis against
temperature on the xaxis.
 As a reference, the intersection point of the curve at 25°C
and 1 atm is highlighted by a circle, with
straight lines extending from the circle to the xaxis and
yaxis for easy visualization of the reference point.

Pressure Range:
 The user can manually set the maximum pressure
for the plot via a text box, allowing the graph to scale
according to the desired pressure range.
 By default, the maximum pressure is set to 2 atm
or 202650 Pa so that the boiling points
for selected compounds are conveniently located near the
midpoint of the yaxis.

Data Set:
 The calculated numeric values (data points) for a plot is
stored in a multiline text field on the
right side of the calculator.
 These data points represent the temperaturepressure
relationship for the selected compound and can be copied by
clicking the "Copy to Clipboard" button.

Advanced Plotting:
 Once copied, the data can be pasted using a more
advanced plotting tool in CHEMIX School e.g Binary Plot
for further analysis, custom visualizations, or additional
processing and storing.
Using the ClausiusClapeyron Calculator &
Plotter

Select a Compound and Plot the
Graph:
 Choose the compound from the dropdown list. This will
automatically generate the graph of vapor pressure vs.
temperature.
 Input Parameter  Set Maximum Pressure:
 Set the temperature $T_2$
and pressure $P_2$
in the corresponding text fields.
 Select the appropriate units for both ${T}_{2}$
(Kelvin, °C, or °F) and $P_2$
(Pa, atm, or mmHg) from the dropdown lists.
 Enter the desired maximum pressure for the plot, or leave
it at the default 2 atm to ensure that
boiling points appear midway on the plot.

Copy Data:
 Simultaneously as the plot is generated, the data points
will appear in the text field on the right.
 To use these data points in external applications, click
the "Copy to Clipboard" button.

Advanced Plotting:
 Paste the copied data into an CHEMIX School advanced
plotting tool such as CHEMIX School  Binary Plot to
create more detailed or custom visualizations.
ClausiusClapeyron
Boiling Point Experiment.html
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