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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Peng Zhong on September 22, 2015, 06:54:37 PM

Title: Are there any fast reversible chemical reactions at room temperature?
Post by: Peng Zhong on September 22, 2015, 06:54:37 PM: Hi all,

Are there any chemical equilibrium reactions such that at ROOM TEMPERATURE:

1: if I add 100% more reactants (double the reactant concentration), the reaction goes forward and reach equilibrium fast (less than 5 minutes)

2: if I add 100% more products (double the product concentration), the reaction goes reverse and reach equilibrium at relatively the same rate as in Case 1 (less than 5 minutes)

Thank you
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Borek on September 23, 2015, 02:24:19 AM: Every neutralization reaction will behave this way. I suppose that's not what you are you are interested in, but they definitely fit.
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Peng Zhong on September 23, 2015, 01:26:31 PM: Thank you, but I am looking for reactions similar to Habor process or Contact process except their reaction kinetics are very slow at room temperature even if the I put a huge concentration stress.

I am looking for reactions are all gaseous phase and have considerable heat of reaction plus it is readily to react both forward and reverse to reach chemical equilibrium at near room temperature.

I am guess reactions that satisfy this criteria are very rare and maybe even non existence =(

If anyone know of such reaction, please let me know.

Thank you
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Enthalpy on September 23, 2015, 02:39:16 PM: 2NO₂ ::equil:: N₂O₄
Both are gaseous at room temperature under a bit less than 1atm. Beware not very healthy.
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Babcock_Hall on September 23, 2015, 03:00:11 PM: What about the mutarotation of glucose? You might be able to perturb the reaction in only one direction, however.
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Peng Zhong on September 23, 2015, 06:25:21 PM: 2NO2=N2O4 falls into this category but I cannot control the initial concentrations easily because it is hard to add pure NO2 or N2O4 as they always exist as mixture of NO2 and N2O4. For example, I can't increase the concentration of NO2 (unless I change the temperature) in the mixture of NO2 and N2O4 because any NO2 I try to add already is a mixture of NO2 and N2O4 with the same molar ratio to the system I try to add to.

If the chemical reaction has the form

A+B=C

then I can modify the initial concentrations easily by simply adding pure A or pure B into the system because A or B by itself cannot have equilibrium mixture of A,B and C.
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Enthalpy on September 24, 2015, 02:46:11 PM: You could try to separate them and use quickly one compound. Say, heat strongly to concentrate one compound, cool fast to room temperature and inject in the mixture. 2NO₂ ::equil:: N₂O₄ taking a few minutes, it must be feasible.

Maybe some sort of solvent or adsorbent can select one of the compounds?
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Enthalpy on September 24, 2015, 02:51:11 PM: The dissolution of CO₂ in water.
You can monitor it through the pH.
With >1atm CO₂, the reverse reaction is fast, as it can make bubbles.
Title: Re: Are there any fast reversible chemical reactions at room temperature?
Post by: Peng Zhong on September 24, 2015, 03:12:16 PM: You were saying I can separate NO2/N2O4. Can I use a selective permeable filter to filter one of the compound out instead of heating, because using external heat will just defeat the propose of reaction at room temperature?

Thanks