Phil wrote:
> 
> Hi!
> This is my first time posting here (5 newsgroups).
> I sure would appreciate some advice on a couple of things.
> 
> First, what volumetric ratio is the optimal mixture for combustion of butane
> with air at STP?

Depends what you want out.  For raw temperature, a stoichiometric mix
in pure oxygen.  If you wnat to get work out of it in a real world
engine, other considerations intrude.

> What temperature is required to initiate the combustion reaction?

Not temp necessarily, energy input.  Look up sparks and explosions.  A
little Pt catalyst may set it off spontaneously.  It is a free radical
chain - exponentiation chugs along.

> At what rate would a combustion front propagate through this mixture?

Depends.  Confined or unconfined?  Shape?  Surface/volume ratio? 
Deflagration, explosion, or detonation?

> If volume is held constant before and after combustion, by what amount will
> the temperature of the mixture have increased after the reaction?
> Finally, if the mixture is made leaner, will the temperature increase be
> reduced roughly proportionally to the amount of fuel present?

Doesn't that sound like a poorly stated p-chem homework problem,
folks?

-- 
Uncle Al
http://www.mazepath.com/uncleal/
 (Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf