PC

This function returns a pure component’s critical pressure from thermophysical data sources using its CAS number.

Critical pressure is the pressure at the critical point and is a core input for cubic equations of state, compressibility correlations, and phase behavior screening.

Excel Usage

=PC(CASRN, method)

• CASRN (str, required): CAS Registry Number for the target chemical (-).
• method (str, optional, default: null): Optional data source method name; leave empty for automatic selection (-).

Returns (float): Critical pressure in pascals (Pa).

Example 1: Critical pressure of water

Inputs:

CASRN
7732-18-5

Excel formula:

=PC("7732-18-5")

Expected output:

22064000

Example 2: Critical pressure of ethanol

Inputs:

CASRN
64-17-5

Excel formula:

=PC("64-17-5")

Expected output:

6268000

Example 3: Critical pressure of methane

Inputs:

CASRN
74-82-8

Excel formula:

=PC("74-82-8")

Expected output:

4599200

Example 4: Critical pressure of benzene

Inputs:

CASRN
71-43-2

Excel formula:

=PC("71-43-2")

Expected output:

4907280

Python Code

Show Code

from chemicals.critical import Pc as chemicals_pc

def pc(CASRN, method=None):
    """
    Retrieve the critical pressure of a chemical by CAS number.

    See: https://chemicals.readthedocs.io/chemicals.critical.html

    This example function is provided as-is without any representation of accuracy.

    Args:
        CASRN (str): CAS Registry Number for the target chemical (-).
        method (str, optional): Optional data source method name; leave empty for automatic selection (-). Default is None.

    Returns:
        float: Critical pressure in pascals (Pa).
    """
    try:
        value = chemicals_pc(CASRN=CASRN, method=method)
        if value is None:
            return "Error: Critical pressure data is not available for the provided CASRN"
        return value
    except Exception as e:
        return f"Error: {str(e)}"

Online Calculator

CASRN *

CAS Registry Number for the target chemical (-).

method

Optional data source method name; leave empty for automatic selection (-).