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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: evaderguy89 on May 23, 2005, 06:44:33 PM

Title: burning isopropyl alcohol
Post by: evaderguy89 on May 23, 2005, 06:44:33 PM
My chemistry teacher took an absopure water thing (the big blue ones that are on upsidedown in the disoenser).  He coated the container insides with 25ml 25% isopropyl alcohol.  He then lit a match and placed it over the mouth of the container.  A fire started in the container and after it went out, he tipped the container over, and a small amount of water poured out.  Can someone tell me what happened?  Thanks.
Title: Re:PLEASE HELP EXPLAIN THIS EXPERIMENT!!!!
Post by: evaderguy89 on May 23, 2005, 06:48:47 PM
sorry, but to show that i am thinking about this, i think it might have to do with the combustability of the isopropyl alchoal gasses.  
Title: Re:PLEASE HELP EXPLAIN THIS EXPERIMENT!!!!
Post by: Donaldson Tan on May 23, 2005, 07:25:07 PM
2C3H7OH + 9O2 -> 6CO2 + 8H2O

complete combustion of alchohol (and hydrocarbon) produces water.
Title: Re:PLEASE HELP EXPLAIN THIS EXPERIMENT!!!!
Post by: evaderguy89 on May 23, 2005, 08:18:53 PM
ok, thanks for the help so far.  why does the alchoal vapor react like this though?
Title: burning isopropyl alcohol
Post by: Donaldson Tan on May 23, 2005, 08:25:41 PM
the reaction produces water in vapour state. the hot water vapour rises above the flame, then cool down at the container inner surface to condense.
Title: Re:burning isopropyl alcohol
Post by: evaderguy89 on May 23, 2005, 09:04:20 PM
thank you so much!  is there anything i should know about the molecules taking place in this reaction?
Title: Re:burning isopropyl alcohol
Post by: evaderguy89 on May 23, 2005, 09:26:57 PM
but where does the flame come from?
Title: Re:burning isopropyl alcohol
Post by: Donaldson Tan on May 23, 2005, 09:29:24 PM
the flame comes from burning ethanol. energy is given out as light and heat.
Title: Re:burning isopropyl alcohol
Post by: hmx9123 on May 23, 2005, 11:31:10 PM
You may also want to note that the majority of the water doesn't come from the isopropyl alcohol itself, but from the solution poured in.  You said it was 25%.  That means that 75% of the original liquid that was poured into the container was water.  Kind of anti-climactic: you pour water in, you pour water out.  Wow.
Title: Re:burning isopropyl alcohol
Post by: constant thinker on May 24, 2005, 08:56:12 PM
Another note I'd like to add is:
Ispropanol burns easily mainly because it vaporizes easily. It doesn't burn very hot. It seams to completely combust in the air easily. The vapor is poisionous and causes sickness easily (throwing up) if breathe in to much.

Ok it was more than one but o well. These conclusions are from my own fun and not fun.