Talk:MRD:sk4915

Feedback

Thank you for the effort! I assume you ran out of time when writing up as a number of answers are missing, but please have a look at this feedback:

Exothermicity Please read this paragraph carefully, as I fear you have a significant misunderstanding about thermodynamics here: "The reaction F + H2 is exothermic which means that some of the kinetic energy used to cause the reaction is stored in the newly formed F-H bond, which is much stronger than the previous H-H bond." In an exothermic reaction energy is released from the molecule to the surroundings (i.e. the expelled atom). Thus, the energy of the F-H bond must be lower than that of the H-H bond. In other words, the energy of the H-H bond is used to form the F-H bond and additionally give off heat. A strong bond requires a lot of energy to break up; that means it has a very low energy (very large negative number). A weak bond on the other hand requires little energy to break, having an energy more close to zero (small negative number). When a weak bond breaks and a strong one forms instead, less energy is stored in the strong bond than in the weak one and the excess is given off as energy to the environment. If you have a trouble with this concept, feel free to contact me to discuss!

Transition State properties

This is a 2D problem, meaning that there is not only one gradient, but two! A Transition State is located at a saddle point, which is an extreme point with respect to both axes. So while it is true that both gradients are zero, this also holds for 2D-maxima and 2D-minima. To distinguish the three from one another, consider their second derivatives. The alternative name "minimax" for a saddle point might be a good hint!

HHH trajectories

In the fourth, unsuccessful, trajectory you claim that the lone atom would not possess enough energy. Trajectory 4 is however initialised with more energy than trajectory 3, which itself is successful. Therefore, the sum of energies cannot be the cause for reactivity by itself. Can you come up with a different explanation? Consider running some more experiments to get more data.

TS theory

While it is true that QM is neglected in the TS theory, there are many more shortcomings of the theory. One is connected to trajectory 4 above. If you look closely at the PES, you can see that geometry crosses over into the product territory, but then reverts back. What could cause this?

FHH system

Please include figures with all your answers. Any scientific claim you make has to be backed up by data! You need to convince your reader that you're telling the truth and the only way to do so is to present the raw data you have collected in your experiments! For example your reported TS geometry is significantly off. I as a reader have two options: Either I believe you, necessarily doubting established results, or I reject your claim. If you really have something worth doubting prior knowledge, you need to support my shift in perspective with even better new knowledge!--Bg1512 (talk) 15:05, 11 May 2017 (BST)