for my thesis i calculated the ring-strain of a molecule by MP2 on the computer. I was wondering if there is an easy possibility to get the experimental value of the ring strain. I guess I have to combust the compound and somehow calculate it from the combustion-enthalpy. My Problem is, that there is no access to the open form of the molecule to compare it. Is there still a way to calculate it? I thought of the Hess-law maybe there is a way with some standard values? It is an organic molecule only containing C, H and O.