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Author: Subject: Amount of H2 required
mayilvaganan
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[*] posted on 21-10-2016 at 05:53
Amount of H2 required


4H2 + CO2 --> CH4 + 2H20 .

What is the volume of hydrogen required (in cu.m or cu.m/h) if it combines with 490 cu.m/h of CO2 to produce 575 cu.m/h of CH4?
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AJKOER
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[*] posted on 21-10-2016 at 06:56


A more fundamental question, ask your teacher if the cited volume of methane produced is measured at a different temperature than the CO2?

If the teacher cannot give an answer or says no, I think you may have a much bigger problem,
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Metacelsus
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[*] posted on 21-10-2016 at 08:49


To elaborate, something is odd with this question. Assuming ideality and constant temperature and pressure, each mole of gas occupies the same volume. Thus, 490 cubic meters of carbon dioxide should produce 490 cubic meters of methane if the temperature and pressure are constant and the gases can be considered ideal.



As below, so above.

My blog: https://denovo.substack.com
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Chemetix
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[*] posted on 21-10-2016 at 13:03


I am going to say that you need 4 mol of H2 (at some standard temperature and pressure) and 1 mol of CO2 also at the same temp. and pressure. Ergo, H2 volume is 4 times the volume of CO2. It gets complicated when you start playing with rates because the arrow would not point one way exclusively, in fact the arrow is more favoured running the other way( making hydrogen and CO2 but at high temperature).

But I don't think this is a chemical engineering question, more a beginners fundamental chemistry sort of thing.
So the principle of 1mol of gas occupying 22.4l at STP is likely the point being made.
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aga
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[*] posted on 21-10-2016 at 13:46


STP changed a while back, as in 34 years ago.

IUPAC STP is 273K at 100kPa

It throws the 22.4 thing out a little.

Just enough to lose points in an exam if the examiner still uses the older definition.




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Chemetix
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[*] posted on 21-10-2016 at 14:16


Damn I've just given away my age

But not that old...Aus used the 22.4 value only up until somewhat recently in the education system (10 yrs? exactly when I cant remember) And started using SLC standard laboratory conditions, which give a molar volume of 24.5L.

The IUPAC STP will give a molar volume of 22.71L. This being an international site makes assumptions about which definition is being used sometimes difficult

[Edited on 21-10-2016 by Chemetix]
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[*] posted on 21-10-2016 at 14:46


The 'S' in STP is for 'Standard' so some measure has to be adopted by all.



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