физики, химики, ау!

[jayrandom]

Мне нужна помощь спецов. emelja, Михаил Игоревич, anyalev, azgar, b_my - буду очень рад реакции. Вопрос: насколько следующая цитата представляет ортодоксальное мнение современной науки? (курсив мой - jayrandom):

Это позволяет нам сделать следующий вывод: кинетическая энергия молекул есть ни что иное, как энергия фотонов, поглощенная атмосферой и другими веществами поверхности планеты. Теперь существует термин для этого излучения — «плененное излучение». Наибольшее количество накопленной лучистой энергии связано с водой океана.

Именно признание факта, что кинетическая энергия молекул НЕ ЕСТЬ собственное свойство молекул, а результат поглощенных фотонов — позволяет рассматривать кинетическую энергию молекул, как энергию «плененного излучения» — этот термин введен в теории лазеров по отношению к накапливаемому излучению.
-- П.Г.Кузнецов, О.Л.Кузнецов, Б.Е.Большаков, "Система природа-общество-человек. Устойчивое развитие."

Буду очень благодарен за.

Comments

Re: Только если/когда будет время/желание

[anyalev.livejournal.com]

По поводу теории по подбору катализаторов, если отвечать коротко, то теория называется "методом тыка".

Now I am switching to English, since it is easier that way. Question 1: Most of the catalysts used today in synthetic organic chemistry are metal based. That means there is a metal with some ligands attached to it that dictate its electronic properties and geometry. For the metal to be used as a catalyst it has to satisfy at least one of the two following conditions, and sometimes both are necessary. First of all the metal has to have an open coordination site for the substrate to attach to it. To put in simple terms the metal has to have a guest room iн the house, and that means free molecular orbitals. That is why many of the catalyst that we have today are made with transition metals, such as ruthenium and palladium. The other condition is the ability to exist in multilple oxidation states and it is the shutelling of the metal between the oxidation states that is one of the driving forces of the reaction.

There is a relatively new field in the catalytic chemistry which is looking at utilizing non-metal catalyst. For example, proline is a very common non-metal catalyst. A lot of times people are looking at short peptides to be used as the catalysts. Which brings us to you second question. Technically, the enzymes can be used as a catalysts in organic reaction, but the problem is that most of the organic reactions do not work in water, but work in non-polar organic solvents. Now, some enzymes can function in non-polar environment, but many can not, and as far as I know it is difficult to predict. However, if you have an organic reaction that works in water then enzyme would be a catalyst of choice, since it is environmentally benign as opposed to a metal catalyst. And of course, the pharmaceutical company would love this kind of reaction because it will keep FDA very very happy.

A lot of times enzymes can serve as a model for catalyst design. If you know the active site of an enzyme you can design a catalyst that would contain the structural motive but overall would be a much smaller molecule. That is why you see short peptides being used as catalysts so often.

With regard to question 3. Any chemist will tell you that the reason why catalase is more effective than platinum in this regard is because it more effectively lowers the transition state of the reaction, but why is catalase in turn more effective in this instance noone truly knows. There are some theories, but basically its like asking why 2x2=4. That's just the way it is.

Question 4: the short answer is no, there is no such theory. Predictions are still hard to do in chemistry, the best you can do is an educated guess.

Question 5: as far as reading goes the best journals for non-professionals to my knowledge are Science and Nature. Things that are described there usually have significant impact on the society in general, rather than just on scientific community, and the description is more general and more user friendly. You can also ask me and I'll try to help you to the best of my knowledge:).

Надеюсь, я тебя не совсем запутала.

[jayrandom.livejournal.com]

Нет, вовсе не запутала, спасибо большое - я подозревал, что дело обстоит подобным образом, и ты подтвердила мои опасения насчёт метода научного тыка (благодаря тебе я даже знаю новое выражение - "educated guess" :) Это в смысле общей картины.

However, I'm still interested in the details.

6. Are there any non-redox reactions that are facilitated by catalysts? As a dummy I imagine a re-organization of positive and negative ions of two soluble salts that lead to some unsoluble product. Is it possible to speed up or slow down such a reaction by using catalysts?

7. I have the Periodic Table on my desk. It lists the orbitals of Ruthenium as 2-8-18-15-1 and Palladium as 2-8-18-18-0. Are they the same orbitals you are talking about? If so, how do I know if there are free guest rooms? Isn't there always some free room until all the levels fill up (as in case of Noble Gases)? Or you mean only the last level (1 and 0 in the case of Ru and Pd)?

8. Is there any way to determine for any particular element, what are the valid oxidation states of this element? Or you simply experiment and then learn by heart that both Cu<sup>+1 and Cu+2 exist?

9. What is bad about a reaction working in a liquid that is different from water (except for the need to re-create this liquid for the purpose of that particular reaction)?

10. Just wondering - why is an organic catalyst more benign to the environment than a metallic one? Is it because you can "burn" it before disposing of? Or you just pour it out, hoping that it won't facilitate any unwanted reaction in the sewer pipes? :)
Or FDA is afraid of some fraction of the catalyst accidentally getting into the pill?</sup>