TITLE: Burning alcohol vapor
QUESTION [4 upvotes]: Let's imagine a plastic container, sealed closed. We fill half of it with alcohol, then we generate a spark.
The question is: can the mixture of alcohol and air burn, or do we need a hole to let air in/out?

REPLY [0 votes]: The question is: does the
  air+alcohol-gas burn creating a big
  pressure or does the container need of
  a little hole to burn?

Strange "need of a little hole", What does that mean? 

The question was: do we need of hole
  to start the ratio of oxygen+alcohol

Another time strange "need of hole". And on the whole two rather different questions.
One thing I can say: In a container with alcohol vapor (I assume ethyl alcohol is meant) 
and air one will have 

40 mmHg partial pressure of ethanol at 19 °C
720 mmHg partial pressure of air  

This makes 40/760 = 5.3  vol-% of ethanol. 
A view in tables says that ethanol has 
Lower explosive limit (LEL) 3.3 vol% 
Upper explosive limit (UEL) 19 vol% 
Answer is: Your container will explode, the liquid ethanol 
will be sprayed around, burning. I'd prefer to be several
dozens of meters away from such "experiments", at least.
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