Methane Fireball

With less than two weeks worth of working days left to go before the summer holidays, you might say, why start a blog now.

Simple. I had the idea, I am excited about it and realistically this is not something I will want to do come September with the business entailed and possibly an inspection.

Anyway, my students often get treated to a mini pyrotechnics show at this time of year, with some challenging questions of course. The timeless methane fireball: in a tub; in the air; on my hand; with pure oxygen; and my favourite: in a 500ml plastic bottle. In the case of the bottle, the best bang is achieved when the correct amounts of each gas (methane and oxygen) are added.

My questions to you:
1) What would be the balanced symbol equation for the complete combustion of methane?
2) Using this equation, what volumes of methane and oxygen would I need in a 500ml bottle for complete combustion to happen with no unused reactants?

I would love to have a video of me doing this, however since it is late and I can't find one in my archives, here is a link which is pretty much what I do.