Cross-reference Chemical formula with CAS

[defencedog]

As per author request I am starting this thread

In following example file CAS is retrieved when chemics throws ValueError indicating unavailablity of said chemical in the database or it requires additional information (CAS reference)

import chemics as cm

formula = input("Chemical Formula e.g CH4, H3N, ClH = ")
press = float(input("Process pressure kPaA = "))
temp = float(input("Process temperature degC = "))

p = press*1000      # Absolute pressure [Pa]
tk = temp+273.15    # temperature of gas [K]

def out_():
	mw = gas.molecular_weight
	rho = gas.density()
	cp = gas.heat_capacity()
	k = gas.thermal_conductivity()
	mu = gas.viscosity() / 1000
	print(f'\n{formula} gas properites:')
	print(f'molecular weight      {mw:.2f} g/mol')
	print(f'density               {rho:.3f} kg/m³')
	print(f'heat capacity         {cp:.3f} J/(mol⋅K)')
	print(f'thermal conductivity  {k:.3f} W/(m⋅K)')
	print(f'viscosity             {mu:.3f} cP')
	print('Note: in SI units 1 cP = 10⁻³ Pa⋅s = 1 mPa⋅s')

try:
	gas = cm.Gas(formula, tk, p)
	out_()
except Exception as error:
	print(f'\n{error}')
	try:
		import cirpy as cir
		name = input('Write gas full-name or formula = ')
		cas_ = cir.resolve(name, 'cas')
		if type(cas_)==list: # multiple cas retrieved
				print('Possible CAS:', *cas_, sep='\n- ')
				cas_f = input("Write proper CAS = ")
		else:
				print(f'\nPossible CAS: {cas_}')
				cas_f = cas_
		gas = cm.Gas(formula, tk, p, cas_number=cas_f)
		out_()
	except Exception as error:
		print(f'\n{error}')