Pyrotechnics

Disclaimer: I am a qualified and experienced Chemistry Teacher; I have done these demonstrations many times and I know what I am doing. I have also done a thorough risk assessment. Please don't try to copy me.

That aside, I hope you enjoy these videos.

1) Fireball on hand

2) Fireball with pure oxygen

Questions
1) (Key Stage 3) What are the energy transfers involved in a methane fireball?

2) (GCSE) Are the products identical when pure oxygen is used, compared to when the methane is ignited in the air only? Explain your answer (using equations if possible)

3) (A-level) An average methane fireball is 500dm³
a. How many moles of methane gas is this?
b. What mass of methane does this equate to?
c. How many moles of oxygen is required for complete combustion?
Show your working