we now consider intramolecular forces. for one mole of rigid diatomic ideal gas, ubond is the additional energy in the chemical bonds holding the atoms together, which can be taken as a constant. the molar internal energy is then: dealvtrt on - ubond write down the internal energy for the same gas in its monatomic form. you are given that at to=3000k. po 105pa, the monatomic and diatomic forms of gas have the same chemical potential. calculate the equation for the p, t phase boundary between diatomic and monoatomic gases. sketch this phase diagram, explaining under what circumstances we might observe (i) a monatomic gas (ii) a diatomic gas (ii) a mixture of monatomic and diatomic molecules 8. a plasma is a phase of matter so hot that the electrons escape the coulomb attraction of the nuclei and move as free particles. by considering the hydrogen atom as a diatomic molecule comprising an electron and a proton bound by ubond 13.6ev, estimate the minimum temperature of a hydrogen plasma.