def Diff_vapor(t_boil, P_abs, Massl, Massh, nul, nuh):
    """
    Calculates the diffusion coefficient of vapor.
    Parameters
    ----------
    Massl : float
        The molar mass of the low-boilling component, [g/mol]
    Massh : float
        The molar mass of the high-boilling component, [g/mol]
    t_boil : float
        The boiling temperature of the low-boiling component, [K]
    P : float
        The absolute pressure of the column, [Pa]
    nul : float
        The molar volume of solute, [sm**3/s]
    nuh : float
        The molar volume of solvent, [sm**3/s]
    Returns
    -------
    Diff_vapor : float
        The diffusion coefficient of vapor, [m**2/s]
    References
    ----------
    Романков, страница 234, формула 6.25
    """
    return 4.22e-2 * t_boil**(3/2) * ((1/Massl) + (1/Massh))**0.5 / (P_abs * ((nul)**0.66 + (nuh)*0.66)**2)