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### Topic: Determining what reaction is more favourable.  (Read 638 times)

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#### JArchy123

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##### Determining what reaction is more favourable.
« on: December 22, 2021, 08:30:02 PM »
I am doing a project at the minute with three reactions occurring. The reactions include:

CH4 + H2O --> CO + 3H2
CO + H20 <--> CO2 + H2
CH4 + 2H2O <--> CO2 + 4H2

My lecturer and I have assumed the first reaction has a CH4 conversion of 95% with the flow rate of both the CH4 and H2O being 134.4753 mol/s. If I have the 95% conversion, I am wondering how much H2O would be provided to each of the other two steps; that is assuming the other 5% of the CH4 is going to the other steps.

#### Orcio_87

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##### Re: Determining what reaction is more favourable.
« Reply #1 on: December 23, 2021, 09:13:08 AM »
More favorable reaction is the one with a higher reaction constant (K).

#### Corribus

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##### Re: Determining what reaction is more favourable.
« Reply #2 on: December 23, 2021, 01:27:29 PM »
My lecturer and I have assumed the first reaction has a CH4 conversion of 95% with the flow rate of both the CH4 and H2O being 134.4753 mol/s.
Why would you assume this? And what is the flow rate related to? There doesn't seem like enough information about your experiment to answer this question.
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#### JArchy123

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##### Re: Determining what reaction is more favourable.
« Reply #3 on: December 23, 2021, 01:59:00 PM »
My colleagues and I calculated a mass balance for the conversion of CH4 to CO and H2 for 95% conversion with the flow rates determined for this preliminary mass balance. In addition, I determined the equilibrium constant (K) to be 0.00968 (3.sf) for the second reaction step and 1.27 * 10^10 (3.sf) for the third step.

#### Borek

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##### Re: Determining what reaction is more favourable.
« Reply #4 on: December 23, 2021, 06:39:09 PM »
More favorable reaction is the one with a higher reaction constant (K).

Not necessarily, kinetics might favor the less thermodynamically likely one.
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#### JArchy123

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##### Re: Determining what reaction is more favourable.
« Reply #5 on: December 24, 2021, 09:54:23 AM »
How would I then determine which one is more favourable?

#### Corribus

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##### Re: Determining what reaction is more favourable.
« Reply #6 on: December 24, 2021, 11:15:10 AM »
The first step is defining what you mean by "more favorable".
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#### Orcio_87

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##### Re: Determining what reaction is more favourable.
« Reply #7 on: December 24, 2021, 03:13:22 PM »
Quote
The first step is defining what you mean by "more favorable".
At given time (5, 10 or 30 min.) 95 % of CH4 was converted to CO and H2. If given more time, rest of the H2O will react with the CO or rather with the remaining 5 % of CH4 ? (he is asking about yield of the two next reactions).

#### Corribus

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##### Re: Determining what reaction is more favourable.
« Reply #8 on: December 26, 2021, 05:38:16 PM »
He asked what is more favorable. "Favorable" in chemistry is not defined without additional context. Thermodynamic and kinetic favorability are two different things.
What men are poets who can speak of Jupiter if he were like a man, but if he is an immense spinning sphere of methane and ammonia must be silent?  - Richard P. Feynman