One more question about the Austrian instrument
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The O-style instrument is used to analyze synthetic cycle gas, whose components include hydrogen, nitrogen, methane, inert gases, and ammonia. The analysis process is as follows: 20 ml of sample gas is taken, mixed with 80 ml of air, and fed into an explosion vessel; after the explosion, the volume is recorded. The gas is then sent to a sodium hydroxide solution to absorb the carbon dioxide present, and the volume after that is recorded. The calculation principle is that it is the carbon dioxide generated by the explosion of methane that is absorbed in the sodium hydroxide solution, while in the explosion vessel, it is methane and hydrogen that react. My question is: where does the ammonia go? Does it explode inside the explosion vessel? How should it be calculated? This post was last edited by chen3jun on 2009-4-5 at 17:14
Ammonia was not involved in the explosion; it is highly soluble in water, and it should have been removed using absorption methods in advance, and eliminated with water before being introduced into the explosion vessel.
Before entering the gas cylinder, the sample gas must be treated with sulfuric acid solution to remove ammonia; otherwise, the volume of the gas collected will be inaccurate! I’m not sure what the levels of methane and hydrogen in your circulating gas are; it seems to me that the ratio of your sample gas to air isn’t correct! You can calculate it by yourself! We use 25 ml of sample gas plus 75 ml of air! Ammonia needs to be measured separately: Take a predetermined amount of sulfuric acid standard solution (1 ml or 10 ml, depending on the level of ammonia content), add methyl red indicator, and add 100 ml of water. Slowly pass the sample gas through the sulfuric acid solution and into a volumetric cylinder; stop the flow of gas when the solution changes from red to yellow. Read the value from the volumetric cylinder and calculate the ammonia content!
The air ratio is fine; I’ve done the calculations. As long as we pay attention to changes in concentration, it’s acceptable to use either 80 or 75 ml of air. We use more air perhaps to ensure there is sufficient oxygen available for the explosion when the hydrogen and methane levels are high. If we want to determine the ammonia content, the method is the same as yours. What I mean is that in routine analyses, the ammonia content can be ignored (it’s usually around 2.0). So, if ammonia is also introduced into the explosion vessel, will it participate in the explosion reaction? What is the equation for that? Can the ammonia content be calculated as well?
I don’t know what solution is in your gas meter, level bottle, and explosion bottle; I assume it’s the same as ours, that is, a sulfuric acid solution. Sulfuric acid can absorb ammonia, and since the ammonia concentration isn’t high, it can be completely absorbed right away without participating in any explosive reaction!
Did you take a 20ml sample gas or air? It’s inconsistent!
Thank you for your thorough explanation. Unfortunately, I don’t have the authority to assign points here. 20 ml should be taken as the sample volume; since the gas syringe contains dilute sulfuric acid, a small amount of ammonia will be absorbed. In other words, our analysis results show the composition of gases other than ammonia.
Just give me a bit more on your territory! :lol