def Na2S(mw_atmos, mh=1):
    """Defines properties for Na2S as condensible"""
    if mh != 1:
        raise Exception(
            'Alert: No M/H Dependence in Na2S Routine. Consult your local theorist to determine next steps.'
            )
    gas_mw = 78.05
    gas_mmr = 1.97e-06 * (gas_mw / mw_atmos)
    rho_p = 1.856
    return gas_mw, gas_mmr, rho_p
